Define atomic number .

Atomic number is the number of protons in the nucleus of an atom. It is unique to each element and determines the element's position in the Periodic Table.

True or False? Metals are found to the right of the staircase line in the Periodic Table.

False. Metals are found to the left of the staircase line. Non-metals are found to the right.

How are elements arranged in the Periodic Table?

Elements are arranged in order of increasing atomic number , from left to right across the table.

In the Periodic Table, elements in the same .......... share similar chemical properties because they have the same number of .......... electrons.

In the Periodic Table, elements in the same group share similar chemical properties because they have the same number of outer electrons.

Define group (in the context of the Periodic Table).

A group is a vertical column in the Periodic Table containing elements that share the same number of outer electrons and similar chemical properties.

Why do elements in the same group of the Periodic Table have similar chemical properties?

Elements in the same group have the same number of outer electrons, and it is the number of outer electrons that determines how an element reacts.

True or False? Hydrogen is a metal because it is positioned on the far left of the Periodic Table.

False. Hydrogen is a non-metal . It is an exception — its position on the far left does not make it a metal.

Electrons fill shells .......... to the nucleus first, and each shell has a .......... number of electrons it can hold.

Electrons fill shells closest to the nucleus first, and each shell has a maximum number of electrons it can hold.

State the electron arrangement of an aluminium atom (atomic number 13).

The electron arrangement of aluminium is 2,8,3 . The first shell holds 2, the second holds 8, and the remaining 3 electrons go in the third shell.

How does the group number of an element relate to its electron arrangement?

The group number tells you the number of electrons in the outer shell of an atom of that element.

An atom is the smallest part of an element that retains the properties of that element. Atoms are made of even smaller particles called subatomic particles.

Name the three subatomic particles found in an atom.

The three subatomic particles are: Protons Neutrons Electrons

True or False? Protons and electrons are both found in the nucleus of an atom.

False. Only protons and neutrons are found in the nucleus. Electrons are found in shells that orbit the nucleus.

The nucleus of an atom contains .......... and .......... , and carries an overall .......... charge.

The nucleus of an atom contains protons and neutrons , and carries an overall positive charge.

Why is an atom overall electrically neutral?

An atom is electrically neutral because the negative charge of each electron exactly cancels out the positive charge of each proton , and the number of electrons equals the number of protons.

An ion is a charged particle formed when an atom loses or gains electrons to achieve a full outer shell.

True or False? An electron has the same relative mass as a proton.

False. An electron has a relative mass of 1/2000 (almost 0), whereas a proton has a relative mass of 1.

How is a positive ion formed from a neutral atom?

A positive ion is formed when a neutral atom loses electrons, leaving it with more protons than electrons and an overall positive charge.

A neutron has a relative mass of .......... and a charge of .......... , so it contributes mass but no charge to the atom.

A neutron has a relative mass of 1 and a charge of 0 (neutral) , so it contributes mass but no charge to the atom.

Mass number is the total number of protons and neutrons in the nucleus of an atom. It is shown at the top left in nuclide notation.

In nuclide notation, where is the atomic number written and what does it represent?

The atomic number is written at the bottom left of the symbol and represents the number of protons in the nucleus.

The number of neutrons in an atom is found by subtracting the .......... from the .......... .

The number of neutrons in an atom is found by subtracting the atomic number from the mass number .

True or False? A neutral atom always has the same number of protons and electrons.

True. In a neutral atom there is no overall charge, so the number of electrons equals the number of protons.

How do you find the number of electrons in a positive ion from its nuclide notation?

For a positive ion, subtract the charge value from the number of protons. For example, a 2+ ion has lost 2 electrons, so electrons = protons − 2.

What is nuclide notation ?

Nuclide notation is a standard shorthand that uses the element symbol with the mass number (top left), atomic number (bottom left) and charge (top right) to describe a specific atom or ion.

A potassium atom has an atomic number of 19 and a mass number of 39, so it has .......... protons, .......... electrons and .......... neutrons.

A potassium atom has an atomic number of 19 and a mass number of 39, so it has 19 protons, 19 electrons and 20 neutrons.

True or False? A sulfide ion (S 2- ) has fewer electrons than a neutral sulfur atom.

False. A sulfide ion has gained 2 electrons, so it has more electrons than a neutral sulfur atom, not fewer.

State the formula for calculating the number of neutrons in an atom.

The formula is: number of neutrons = mass number − atomic number

Why is the atomic number unique to each element?

The atomic number is unique to each element because it defines the number of protons, and changing the number of protons changes the element itself.

Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons. They therefore have the same atomic number but different mass numbers.

True or False? Isotopes of an element have different chemical properties because they have different mass numbers.

False. Isotopes have the same chemical properties because they have the same number of outer electrons. Different mass numbers only affect physical properties.

State two ways of writing the name of an isotope.

An isotope can be written as: The element name (or symbol) followed by a dash and the mass number — for example, carbon-14 or C-14 In nuclide notation showing the atomic number and mass number

Chlorine-35 and chlorine-37 are isotopes. They both have .......... protons but chlorine-37 has .......... more neutron(s) than chlorine-35.

Chlorine-35 and chlorine-37 are isotopes. They both have 17 protons but chlorine-37 has 2 more neutron(s) than chlorine-35.

Define relative atomic mass .

Relative atomic mass is the weighted average mass of an element's atoms, taking into account the mass and abundance of each isotope.

Why are relative atomic masses often not whole numbers?

Relative atomic masses are often not whole numbers because most elements exist as a mixture of isotopes, and the relative atomic mass is the weighted average of all isotope masses according to their abundances.

True or False? If the relative atomic mass of an element is closer to the lighter isotope, the lighter isotope is more abundant.

True. The relative atomic mass is always pulled towards the more abundant isotope, so if it is closer to the lighter isotope, that isotope is present in greater proportion.

Chlorine has two isotopes: chlorine-35 and chlorine-37. Its relative atomic mass is 35.5. How does this tell you which isotope is more abundant?

A relative atomic mass of 35.5 is closer to 35 than to 37, which shows that chlorine-35 is the more abundant isotope in a natural sample of chlorine.

If two isotopes were present in exactly equal amounts, the relative atomic mass would be exactly .......... between their two mass numbers.

If two isotopes were present in exactly equal amounts, the relative atomic mass would be exactly halfway between their two mass numbers.

Define covalent bond .

A covalent bond is a bond formed when two positive nuclei are held together by their common attraction for a shared pair of electrons.

True or False? Non-metal atoms share electrons with other non-metal atoms to obtain a full outer shell.

True. Non-metal atoms share electrons with other non-metal atoms, and this sharing allows each atom to achieve a full outer shell of electrons.

How does a single covalent bond form between two chlorine atoms?

A single covalent bond forms when each chlorine atom shares one of its outer electrons with the other, creating one shared pair of electrons. This gives each chlorine atom a full outer shell of eight electrons.

A .......... bond is formed when two atoms share two pairs of electrons, giving a total of .......... electrons in the bond.

A double bond is formed when two atoms share two pairs of electrons, giving a total of four electrons in the bond.

Why does nitrogen form a triple bond in N 2 ?

Nitrogen is in Group 5 and has five outer electrons, so each atom needs three more to reach a full shell of eight. Each nitrogen atom shares three of its electrons with the other, forming three shared pairs — a triple bond.

True or False? When drawing covalent bonding dot-and-cross diagrams, you should show all electron shells including inner shells.

False. Only the outer shell electrons are shown in covalent bonding diagrams. Inner shells and their electrons are not drawn.

A double bond is a covalent bond formed when two atoms share two pairs of electrons (four electrons in total).

Name the seven diatomic elements.

The seven diatomic elements are: Hydrogen (H 2 ) Nitrogen (N 2 ) Oxygen (O 2 ) Fluorine (F 2 ) Chlorine (Cl 2 ) Bromine (Br 2 ) Iodine (I 2 )

When two atoms form a covalent bond, the .......... nuclei are attracted to the .......... shared electrons between them.

When two atoms form a covalent bond, the positive nuclei are attracted to the negative shared electrons between them.

Define linear molecule .

A linear molecule is one in which all atoms are arranged in a straight line, with two atoms bonded to one central atom. Carbon dioxide is an example.

True or False? Carbon dioxide (CO 2 ) is a linear molecule.

True. Carbon dioxide is linear because two oxygen atoms are bonded to the central carbon atom and all three atoms lie in a straight line.

What two factors determine the shape of a simple covalent molecule?

The shape of a simple covalent molecule is determined by: The number of atoms bonded to the central atom The way the bonds are arranged in space (bond pairs repel each other and spread as far apart as possible)

Water (H 2 O) has an .......... shape because the two hydrogen atoms and the central oxygen atom are arranged in a .......... or 'V' shape.

Water (H 2 O) has an angular shape because the two hydrogen atoms and the central oxygen atom are arranged in a bent or 'V' shape.

National 5ChemistrySQAFlashcardsChemical Changes & StructureAtomic Structure & Bonding Related to Properties of Materials

Atomic Structure & Bonding Related to Properties of Materials (SQA National 5 Chemistry): Flashcards

Exam code: X813 75

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Define atomic number.

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Define atomic number.
Atomic number is the number of protons in the nucleus of an atom.
It is unique to each element and determines the element's position in the Periodic Table.
True or False?
Metals are found to the right of the staircase line in the Periodic Table.
False.
Metals are found to the left of the staircase line. Non-metals are found to the right.
How are elements arranged in the Periodic Table?
Elements are arranged in order of increasing atomic number, from left to right across the table.
In the Periodic Table, elements in the same .......... share similar chemical properties because they have the same number of .......... electrons.
In the Periodic Table, elements in the same group share similar chemical properties because they have the same number of outer electrons.
Define group (in the context of the Periodic Table).
A group is a vertical column in the Periodic Table containing elements that share the same number of outer electrons and similar chemical properties.
Why do elements in the same group of the Periodic Table have similar chemical properties?
Elements in the same group have the same number of outer electrons, and it is the number of outer electrons that determines how an element reacts.
True or False?
Hydrogen is a metal because it is positioned on the far left of the Periodic Table.
False.
Hydrogen is a non-metal. It is an exception — its position on the far left does not make it a metal.
Electrons fill shells .......... to the nucleus first, and each shell has a .......... number of electrons it can hold.
Electrons fill shells closest to the nucleus first, and each shell has a maximum number of electrons it can hold.
State the electron arrangement of an aluminium atom (atomic number 13).
The electron arrangement of aluminium is 2,8,3.
The first shell holds 2, the second holds 8, and the remaining 3 electrons go in the third shell.
How does the group number of an element relate to its electron arrangement?
The group number tells you the number of electrons in the outer shell of an atom of that element.
Define atom.
An atom is the smallest part of an element that retains the properties of that element.
Atoms are made of even smaller particles called subatomic particles.
Name the three subatomic particles found in an atom.
The three subatomic particles are:
1. Protons
2. Neutrons
3. Electrons
True or False?
Protons and electrons are both found in the nucleus of an atom.
False.
Only protons and neutrons are found in the nucleus. Electrons are found in shells that orbit the nucleus.
The nucleus of an atom contains .......... and .........., and carries an overall .......... charge.
The nucleus of an atom contains protons and neutrons, and carries an overall positive charge.
Why is an atom overall electrically neutral?
An atom is electrically neutral because the negative charge of each electron exactly cancels out the positive charge of each proton, and the number of electrons equals the number of protons.
Define ion.
An ion is a charged particle formed when an atom loses or gains electrons to achieve a full outer shell.
True or False?
An electron has the same relative mass as a proton.
False.
An electron has a relative mass of 1/2000 (almost 0), whereas a proton has a relative mass of 1.
How is a positive ion formed from a neutral atom?
A positive ion is formed when a neutral atom loses electrons, leaving it with more protons than electrons and an overall positive charge.
A neutron has a relative mass of .......... and a charge of .........., so it contributes mass but no charge to the atom.
A neutron has a relative mass of 1 and a charge of 0 (neutral), so it contributes mass but no charge to the atom.
Define mass number.
Mass number is the total number of protons and neutrons in the nucleus of an atom.
It is shown at the top left in nuclide notation.
In nuclide notation, where is the atomic number written and what does it represent?
The atomic number is written at the bottom left of the symbol and represents the number of protons in the nucleus.
The number of neutrons in an atom is found by subtracting the .......... from the ...........
The number of neutrons in an atom is found by subtracting the atomic number from the mass number.
True or False?
A neutral atom always has the same number of protons and electrons.
True.
In a neutral atom there is no overall charge, so the number of electrons equals the number of protons.
How do you find the number of electrons in a positive ion from its nuclide notation?
For a positive ion, subtract the charge value from the number of protons.
For example, a 2+ ion has lost 2 electrons, so electrons = protons − 2.
What is nuclide notation?
Nuclide notation is a standard shorthand that uses the element symbol with the mass number (top left), atomic number (bottom left) and charge (top right) to describe a specific atom or ion.
A potassium atom has an atomic number of 19 and a mass number of 39, so it has .......... protons, .......... electrons and .......... neutrons.
A potassium atom has an atomic number of 19 and a mass number of 39, so it has 19 protons, 19 electrons and 20 neutrons.
True or False?
A sulfide ion (S^2-) has fewer electrons than a neutral sulfur atom.
False.
A sulfide ion has gained 2 electrons, so it has more electrons than a neutral sulfur atom, not fewer.
State the formula for calculating the number of neutrons in an atom.
The formula is:
number of neutrons = mass number − atomic number
Why is the atomic number unique to each element?
The atomic number is unique to each element because it defines the number of protons, and changing the number of protons changes the element itself.
Define isotopes.
Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons.
They therefore have the same atomic number but different mass numbers.
True or False?
Isotopes of an element have different chemical properties because they have different mass numbers.
False.
Isotopes have the same chemical properties because they have the same number of outer electrons. Different mass numbers only affect physical properties.
State two ways of writing the name of an isotope.
An isotope can be written as:
1. The element name (or symbol) followed by a dash and the mass number — for example, carbon-14 or C-14
2. In nuclide notation showing the atomic number and mass number
Chlorine-35 and chlorine-37 are isotopes. They both have .......... protons but chlorine-37 has .......... more neutron(s) than chlorine-35.
Chlorine-35 and chlorine-37 are isotopes. They both have 17 protons but chlorine-37 has 2 more neutron(s) than chlorine-35.
Define relative atomic mass.
Relative atomic mass is the weighted average mass of an element's atoms, taking into account the mass and abundance of each isotope.
Why are relative atomic masses often not whole numbers?
Relative atomic masses are often not whole numbers because most elements exist as a mixture of isotopes, and the relative atomic mass is the weighted average of all isotope masses according to their abundances.
True or False?
If the relative atomic mass of an element is closer to the lighter isotope, the lighter isotope is more abundant.
True.
The relative atomic mass is always pulled towards the more abundant isotope, so if it is closer to the lighter isotope, that isotope is present in greater proportion.
Chlorine has two isotopes: chlorine-35 and chlorine-37. Its relative atomic mass is 35.5. How does this tell you which isotope is more abundant?
A relative atomic mass of 35.5 is closer to 35 than to 37, which shows that chlorine-35 is the more abundant isotope in a natural sample of chlorine.
If two isotopes were present in exactly equal amounts, the relative atomic mass would be exactly .......... between their two mass numbers.
If two isotopes were present in exactly equal amounts, the relative atomic mass would be exactly halfway between their two mass numbers.
Define covalent bond.
A covalent bond is a bond formed when two positive nuclei are held together by their common attraction for a shared pair of electrons.
True or False?
Non-metal atoms share electrons with other non-metal atoms to obtain a full outer shell.
True.
Non-metal atoms share electrons with other non-metal atoms, and this sharing allows each atom to achieve a full outer shell of electrons.
How does a single covalent bond form between two chlorine atoms?
A single covalent bond forms when each chlorine atom shares one of its outer electrons with the other, creating one shared pair of electrons. This gives each chlorine atom a full outer shell of eight electrons.
A .......... bond is formed when two atoms share two pairs of electrons, giving a total of .......... electrons in the bond.
A double bond is formed when two atoms share two pairs of electrons, giving a total of four electrons in the bond.
Why does nitrogen form a triple bond in N₂?
Nitrogen is in Group 5 and has five outer electrons, so each atom needs three more to reach a full shell of eight. Each nitrogen atom shares three of its electrons with the other, forming three shared pairs — a triple bond.
True or False?
When drawing covalent bonding dot-and-cross diagrams, you should show all electron shells including inner shells.
False.
Only the outer shell electrons are shown in covalent bonding diagrams. Inner shells and their electrons are not drawn.
Define double bond.
A double bond is a covalent bond formed when two atoms share two pairs of electrons (four electrons in total).
Name the seven diatomic elements.
The seven diatomic elements are:
1. Hydrogen (H₂)
2. Nitrogen (N₂)
3. Oxygen (O₂)
4. Fluorine (F₂)
5. Chlorine (Cl₂)
6. Bromine (Br₂)
7. Iodine (I₂)
When two atoms form a covalent bond, the .......... nuclei are attracted to the .......... shared electrons between them.
When two atoms form a covalent bond, the positive nuclei are attracted to the negative shared electrons between them.
Define linear molecule.
A linear molecule is one in which all atoms are arranged in a straight line, with two atoms bonded to one central atom. Carbon dioxide is an example.
True or False?
Carbon dioxide (CO₂) is a linear molecule.
True.
Carbon dioxide is linear because two oxygen atoms are bonded to the central carbon atom and all three atoms lie in a straight line.
What two factors determine the shape of a simple covalent molecule?
The shape of a simple covalent molecule is determined by:
1. The number of atoms bonded to the central atom
2. The way the bonds are arranged in space (bond pairs repel each other and spread as far apart as possible)
Water (H₂O) has an .......... shape because the two hydrogen atoms and the central oxygen atom are arranged in a .......... or 'V' shape.
Water (H₂O) has an angular shape because the two hydrogen atoms and the central oxygen atom are arranged in a bent or 'V' shape.
Define tetrahedral molecule.
A tetrahedral molecule is one in which a central atom has four bonds pointing to the corners of a tetrahedron. Methane (CH₄) is an example.
True or False?
Ammonia (NH₃) has a trigonal pyramidal shape with four hydrogen atoms bonded to the central nitrogen atom.
False.
Ammonia has a trigonal pyramidal shape, but only three hydrogen atoms are bonded to the central nitrogen atom, not four.
What does a solid wedge represent in a 3D drawing of a molecule?
A solid wedge represents a bond coming out of the page, towards the viewer.
Why do the bonds in a covalent molecule adopt a specific 3D shape?
The electron pairs in the bonds repel each other and push as far apart in space as possible. This repulsion forces the molecule into its most stable shape.
Define intermolecular forces.
Intermolecular forces are weak forces of attraction that exist between separate covalent molecules. They are much weaker than the covalent bonds within each molecule.
True or False?
When a covalent molecular substance melts, the strong covalent bonds inside the molecules break.
False.
When a covalent molecular substance melts, only the weak intermolecular forces between molecules are overcome. The strong covalent bonds within each molecule remain intact.
Why do covalent molecular substances have low melting and boiling points?
Covalent molecular substances have low melting and boiling points because only weak intermolecular forces between molecules need to be overcome when the substance melts or boils. Very little energy is required to break these weak forces.
Covalent molecular substances do not conduct electricity because their molecules are .......... and their electrons are held in .......... bonds, so there are no free-moving charged particles.
Covalent molecular substances do not conduct electricity because their molecules are neutral and their electrons are held in fixed bonds, so there are no free-moving charged particles.
Define covalent network structure.
A covalent network structure is a giant three-dimensional lattice in which all atoms are held together by a vast network of strong covalent bonds throughout, with no separate molecules.
True or False?
Graphite is the only covalent network structure that can conduct electricity.
True.
In graphite, each carbon atom bonds to only three others, leaving one delocalised electron per atom that is free to move along the layers and carry a current.
Why do covalent network structures have extremely high melting and boiling points?
Covalent network structures have extremely high melting and boiling points because a very large amount of energy is needed to break the strong covalent bonds that extend throughout the giant three-dimensional lattice.
Name three examples of covalent network structures.
Three examples of covalent network structures are:
1. Graphite
2. Diamond
3. Silicon dioxide
Covalent network structures are .......... in all solvents because the .......... covalent bonds holding the atoms together cannot be broken by solvent particles.
Covalent network structures are insoluble in all solvents because the strong covalent bonds holding the atoms together cannot be broken by solvent particles.
Define ion.
An ion is a charged particle formed when an atom loses or gains electrons to achieve a stable, full outer shell of electrons.
True or False?
Metal atoms achieve a stable electron arrangement by gaining electrons from non-metals.
False.
Metal atoms achieve a stable electron arrangement by losing their outer electrons. This forms positive ions. Non-metals gain electrons to form negative ions.
Why does a magnesium atom form a 2+ ion?
A magnesium atom has the electron arrangement 2,8,2 and loses its two outer electrons to achieve the stable arrangement 2,8. Losing two negative electrons leaves the atom with more protons than electrons, giving it a 2+ charge.
In an ion-electron equation for a metal, the electrons are written on the .......... side of the equation because the metal atom .......... electrons.
In an ion-electron equation for a metal, the electrons are written on the product (right) side of the equation because the metal atom loses electrons.
Define ionic lattice.
An ionic lattice is a giant, regular, three-dimensional crystal structure in which positive and negative ions are held together by strong electrostatic attractions acting in all directions.
True or False?
The formula NaCl represents a single molecule of sodium chloride.
False.
NaCl is not a molecule. The formula shows the simplest whole-number ratio of ions in the giant ionic lattice — one Na⁺ ion for every one Cl^- ion.
How does ionic bonding form between a metal and a non-metal?
Ionic bonding forms when the metal atom transfers its outer electrons to the non-metal atom. The metal becomes a positive ion and the non-metal becomes a negative ion. Strong electrostatic attraction between the oppositely charged ions holds them together.
Write the ion-electron equation for an oxygen atom forming an oxide ion.
The ion-electron equation is: O + 2e^- → O^2-
Oxygen gains two electrons (shown on the left side) to achieve the stable electron arrangement 2,8 and form the O^2- ion.
Non-metal atoms form .......... ions by .......... electrons to complete their outer shell.
Non-metal atoms form negative ions by gaining electrons to complete their outer shell.
Why do ionic compounds have very high melting and boiling points?
Ionic compounds have very high melting and boiling points because a very large amount of energy is needed to break the strong electrostatic forces of attraction between the positive and negative ions throughout the giant ionic lattice.
True or False?
Ionic compounds conduct electricity when in the solid state.
False.
Although solid ionic compounds contain charged ions, the ions are held in fixed positions in the lattice and are not free to move. They can only conduct electricity when molten or dissolved in water.
What is meant by electrostatic force of attraction in an ionic compound?
An electrostatic force of attraction is the strong force between oppositely charged ions (positive and negative) in an ionic lattice that holds the giant structure together.
When an ionic compound dissolves in water, the .......... molecules attract the ions and pull them away from the lattice. The separated ions become .......... by water molecules.
When an ionic compound dissolves in water, the water molecules attract the ions and pull them away from the lattice. The separated ions become surrounded by water molecules.
How does a molten ionic compound conduct electricity?
When an ionic compound melts, the lattice breaks down and the ions become free to move. The positive ions move towards the negative electrode and the negative ions move towards the positive electrode. This directed movement of charged ions carries the electric current.
True or False?
Ionic compounds generally dissolve well in covalent solvents such as hexane.
False.
Ionic compounds are generally insoluble in covalent solvents. The particles in covalent solvents cannot overcome the strong electrostatic forces holding the ionic lattice together.
What are the two conditions required for any substance to conduct electricity?
For a substance to conduct electricity it must:
1. Contain charged particles
2. Have those charged particles free to move and carry a current
Ionic compounds are typically .......... solids at room temperature because the strong .......... between ions requires a great deal of energy to overcome.
Ionic compounds are typically crystalline solids at room temperature because the strong electrostatic forces of attraction between ions requires a great deal of energy to overcome.
Why are ionic compounds insoluble in covalent solvents but soluble in water?
Water molecules are strongly attracted to the positive and negative ions and can pull them away from the lattice, breaking it apart. Covalent solvent particles cannot generate attractions strong enough to overcome the ionic bonds, so the lattice remains intact.

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