Ionic, Covalent & Metallic Bond (AQA GCSE Combined Science: Trilogy: Chemistry): Flashcards
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Why do atoms form chemical bonds?
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Why do atoms form chemical bonds?
Atoms form chemical bonds to achieve a full outer shell of electrons, which gives them greater stability. Electrons are either transferred between atoms (ionic bonding) or shared between atoms (covalent bonding).
What are the three types of chemical bonding studied at GCSE?
The three types are:
Ionic bonding (between metals and non-metals)
Covalent bonding (between non-metals)
Metallic bonding (in metals and metal alloys)
In ionic bonding, metal ________ lose electrons to form ________ ions, while non-metal ________ gain electrons to form ________ ions.
In ionic bonding, metal atoms lose electrons to form positive ions, while non-metal atoms gain electrons to form negative ions.
True or False?
In ionic bonding, atoms share electrons to achieve a full outer shell.
False.
In ionic bonding, electrons are transferred from metal atoms to non-metal atoms. Sharing electrons describes covalent bonding, not ionic bonding.
What holds the ions together in an ionic compound?
The oppositely charged ions are held together by strong electrostatic forces of attraction between the positive and negative ions.
In covalent bonding, non-metal atoms form bonds by ________ pairs of electrons between them.
In covalent bonding, non-metal atoms form bonds by sharing pairs of electrons between them.
True or False?
Intermolecular forces are a type of chemical bond.
False.
Intermolecular forces are not chemical bonds. No electrons are transferred or shared, and no new compounds are formed. They are typically about one-tenth the strength of a chemical bond.
Define ionic bonding.
Ionic bonding is the strong electrostatic force of attraction between oppositely charged ions. It forms when a metal atom transfers electrons to a non-metal atom, creating a positive ion (cation) and a negative ion (anion).
Positive ions are called ________ and form when atoms ________ electrons.
Negative ions are called ________ and form when atoms ________ electrons.
Positive ions are called cations and form when atoms lose electrons.
Negative ions are called anions and form when atoms gain electrons.
What is the charge on ions formed from Group 1, Group 2, Group 6, and Group 7 elements?
Group 1: 1+
Group 2: 2+
Group 6: 2−
Group 7: 1−
The charge equals the number of electrons lost or gained.
True or False?
A calcium atom loses one electron to form a Ca+ ion.
False.
Calcium is in Group 2 and loses two electrons to form a Ca2+ ion. The size of the charge always equals the number of electrons lost or gained.
In a dot and cross diagram of an ionic compound, what do the square brackets indicate, and where is the ion's charge written?
Square brackets enclose each individual ion. The ion's charge is written as a superscript outside the bracket at the top right.
In magnesium oxide, the magnesium ion has a charge of ________ and the oxide ion has a charge of ________. The formula of magnesium oxide is ________.
The magnesium ion has a charge of 2+ and the oxide ion has a charge of 2−. The formula of magnesium oxide is MgO.
How do you work out the formula of an ionic compound from the charges of its ions? Give an example.
Find the ratio of ions that makes the overall charge zero.
For example, Na+ and O2-: two Na+ are needed to balance one O2-, giving the formula Na2O.
True or False?
When describing how sodium chloride forms, it is correct to say: "sodium transfers its electron to chloride".
False.
Before the electron transfer, the non-metal is a chlorine atom. Only after gaining the electron does it become the chloride ion. The correct phrasing is: sodium transfers its electron to chlorine to form chloride.
Describe the structure of a giant ionic lattice.
A giant ionic lattice is a regular, three-dimensional arrangement of alternating positive and negative ions, tightly packed together and held in place by strong electrostatic forces acting in all directions.
Why do ionic compounds have high melting and boiling points?
Ionic compounds form a giant ionic lattice in which many strong electrostatic forces of attraction act between oppositely charged ions in all directions. A large amount of energy is needed to overcome all of these forces.
In a giant ionic lattice, positive and negative ions are arranged in a regular, ________ pattern, and the electrostatic forces of attraction act in ________ directions.
In a giant ionic lattice, positive and negative ions are arranged in a regular, alternating pattern, and the electrostatic forces of attraction act in all directions.
What are two limitations of the 3D ball and stick model when representing an ionic lattice?
The sticks suggest ionic bonds are directional; in reality, electrostatic forces act in all directions around each ion.
The model shows space between ions that does not exist; the 3D space-filling model is more accurate.
True or False?
Ionic compounds have high melting points because they contain many strong intermolecular forces.
False.
Intermolecular forces exist between molecules in covalent compounds, not in ionic compounds. Ionic compounds contain strong electrostatic forces of attraction between oppositely charged ions in a giant lattice.
Define covalent bonding.
Covalent bonding occurs when non-metal atoms share pairs of electrons to achieve a full outer shell. The bond forms due to electrostatic attraction between the shared electrons and the positive nuclei of both atoms. Covalent bonds are very strong.
What is the difference between bonding electrons and non-bonding electrons in a covalent molecule?
Bonding electrons are the shared pairs of electrons that form the covalent bond between two atoms. Non-bonding electrons (lone pairs) are outer shell electrons not involved in any covalent bond.
When drawing a dot and cross diagram, the shared pair of electrons must be placed ________ the overlapping region. You should only draw ________ electrons, not inner shells.
The shared pair of electrons must be placed inside the overlapping region. You should only draw outer shell electrons, not inner shells.
True or False?
Simple covalent molecules have low boiling points because the covalent bonds within each molecule are weak.
False.
The covalent bonds within molecules are strong. Simple covalent molecules have low boiling points because the intermolecular forces between molecules are weak and require little energy to overcome. It is these intermolecular forces that break on boiling, not the covalent bonds.
The empirical formula of ethene (C2H4) is ________. It shows the ________ whole number ratio of atoms of each element.
The empirical formula of ethene is CH2. It shows the simplest whole number ratio of atoms of each element (C:H = 2:4 = 1:2).
What is one advantage and one limitation of a dot and cross diagram compared to a ball and stick model?
Advantage: shows which atom the bonding electrons come from and how electrons are shared.
Limitation: fails to show the 3D arrangement of atoms or the relative sizes of the atoms.
True or False?
In a dot and cross diagram of water (H2O), each hydrogen atom should show non-bonding (lone pair) electrons on its outer shell.
False.
Hydrogen has only one outer electron. After forming one covalent bond, its outer shell is full with just two electrons (the bonding pair). There are no non-bonding electrons on hydrogen atoms in a dot and cross diagram.
Describe the structure of a metallic lattice.
A metallic lattice consists of a giant, regular arrangement of positive metal ions surrounded by a sea of delocalised electrons that are free to move throughout the entire structure.
What is a metallic bond?
A metallic bond is the strong electrostatic attraction between the positive metal ions and the sea of delocalised electrons surrounding them. This type of bonding occurs in metals and metal alloys.
In a metal, the outer shell electrons become ________, meaning they are free to ________ throughout the entire structure. The atoms that lose these electrons become positively charged ________.
The outer shell electrons become delocalised, meaning they are free to move throughout the entire structure. The atoms that lose these electrons become positively charged metal ions.
True or False?
In metallic bonding, the delocalised electrons are transferred to another substance, similar to ionic bonding.
False.
Unlike ionic bonding, the delocalised electrons in metals are not transferred to another substance. They remain within the metallic lattice and move freely throughout the entire structure.
What does the term delocalised mean when describing electrons in a metallic lattice?
Delocalised means the electrons are not attached to any particular atom. Instead, they are free to move throughout the entire metallic lattice structure, rather than being confined to an individual atom's outer shell.
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