Atomic Structure & the Periodic Table (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Chemistry): Flashcards
Exam code: 0654 & 0973
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Define the term element.
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Define the term element.
An element is a substance made of atoms that all contain the same number of protons. It cannot be broken down into simpler substances by chemical means.
True or False?
A compound can be separated into its elements by physical methods such as filtration.
False.
A compound can only be separated into its elements by chemical means. Physical methods can separate mixtures but not compounds.
A ______ is formed when two or more elements are ______ combined, while a ______ contains substances that are not chemically combined and can be separated by physical methods.
A compound is formed when two or more elements are chemically combined, while a mixture contains substances that are not chemically combined and can be separated by physical methods.
What is the key difference between a compound and a mixture?
In a compound, two or more elements are chemically combined in fixed proportions and cannot be separated by physical means.
In a mixture, substances are not chemically combined and can be separated by physical methods such as filtration or evaporation.
True or False?
All atoms of the same element have the same number of protons.
True.
The number of protons in an atom defines which element it is. All atoms of the same element have the same proton number (atomic number).
Mixtures can be separated by ______ methods such as ______ or evaporation, because the components are not ______ combined.
Mixtures can be separated by physical methods such as filtration or evaporation, because the components are not chemically combined.
Why can a mixture of sulfur powder and iron filings be separated by a magnet, but copper(II) sulfate cannot be separated into copper and sulfur by the same method?
Sulfur and iron in the mixture are not chemically combined, so they retain their individual properties and can be separated by physical means. In copper(II) sulfate, the elements are chemically combined into a compound with different properties from either element alone.
What are the three subatomic particles and where is each found?
The three subatomic particles are protons and neutrons (both found in the nucleus) and electrons (found in shells around the nucleus).
True or False?
Protons and neutrons have the same relative mass but different charges.
True.
Both protons and neutrons have a relative mass of 1. Protons carry a charge of 1+ while neutrons are neutral (charge 0).
The ______ number is the number of protons in an atom, while the ______ number is the total number of protons and neutrons.
The proton number is the number of protons in an atom, while the mass number is the total number of protons and neutrons.
How do you calculate the number of neutrons in an atom?
Number of neutrons = mass number - proton number.
For example, an atom with mass number 23 and proton number 11 has 23 - 11 = 12 neutrons.
True or False?
In a neutral atom, the number of protons equals the number of electrons.
True.
A neutral atom carries no overall charge, so the number of positively charged protons must equal the number of negatively charged electrons.
Why does the mass of an atom come almost entirely from its nucleus?
Protons and neutrons (relative mass = 1 each) are located in the nucleus, contributing almost all of the atom's mass. Electrons have a negligible mass (approximately 1/1840 of a proton) and contribute very little to the total.
An atom with proton number 17 and mass number 35 contains ______ protons, ______ electrons and ______ neutrons.
An atom with proton number 17 and mass number 35 contains 17 protons, 17 electrons and 18 neutrons.
What is the electronic configuration of an atom?
The electronic configuration is a notation showing the number of electrons in each shell of an atom, written as numbers separated by commas. For example, sodium (11 electrons) has the configuration 2,8,1.
True or False?
The first shell of an atom can hold a maximum of 8 electrons.
False.
The first shell can hold a maximum of 2 electrons. The second and third shells can each hold a maximum of 8 electrons.
Electrons fill the ______ closest to the nucleus first. The first shell holds a maximum of ______ electrons and the second a maximum of ______.
Electrons fill the shell closest to the nucleus first. The first shell holds a maximum of 2 electrons and the second a maximum of 8.
How does an element's position in the Periodic Table relate to its electronic configuration?
The period number tells you how many shells are occupied (how many digits the configuration has).
The group number tells you how many electrons are in the outer shell (the last digit).
Shell 1 holds a maximum of 2, shells 2 and 3 each hold a maximum of 8.
For example, chlorine in Period 3, Group VII has the configuration 2,8,7.
True or False?
Elements in the same group of the Periodic Table have the same number of outer shell electrons.
True.
Elements in the same group have the same number of electrons in their outermost shell, which is why they have similar chemical properties.
An element with the electronic configuration 2,8,2 is in Period ______, Group ______, and has ______ electrons in its outer shell.
An element with the electronic configuration 2,8,2 is in Period 3, Group II, and has 2 electrons in its outer shell.
Why are noble gases unreactive?
Noble gases have full outer shells of electrons, making them very stable. Since they already have a full outer shell, they have no tendency to gain, lose, or share electrons with other atoms.
What are isotopes?
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. They have the same proton number but different mass numbers.
True or False?
Isotopes of the same element have identical chemical properties.
True.
Isotopes have the same number of electrons in the same arrangement, so they react in exactly the same way chemically. Their different numbers of neutrons do not affect their chemistry.
Isotopes have the same number of ______ but different numbers of ______, giving them the same ______ properties but different physical properties.
Isotopes have the same number of protons but different numbers of neutrons, giving them the same chemical properties but different physical properties.
How would you write the symbol for carbon-14 using isotope notation?
Carbon-14 can be written as C-14 (or carbon-14). In atomic notation it is written with the mass number 14 as a superscript to the upper left of the symbol C, and the proton number 6 below it.
True or False?
Isotopes of the same element have different physical properties because they have different numbers of neutrons.
True.
Neutrons add mass but do not affect chemical behaviour. Isotopes of the same element differ in mass, which leads to slightly different physical properties such as density, melting point and boiling point.
Why do isotopes of the same element have the same chemical properties?
Chemical properties depend on the number and arrangement of electrons. Isotopes have the same number of protons and therefore the same number of electrons in the same shells. Their different numbers of neutrons have no effect on electron configuration and so do not affect chemical behaviour.
An isotope of hydrogen with 1 proton and 2 neutrons has a mass number of ______ and is written as ______.
An isotope of hydrogen with 1 proton and 2 neutrons has a mass number of 3 and is written as H-3 (or hydrogen-3).
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