What is the atomic number of an element?
The number of protons the element contains
The atomic number identifies elements on the periodic table.
What is the mass number of an element?
The number of protons plus the number of neutrons
The mass number provides information about the total number of subatomic particles in the nucleus.
Which model of the atom places the orbital electrons into specific energy levels or ‘shells’?
Bohr model
This replaced the ‘planetary’ model proposed by Rutherford
How do electrons fill shells in atoms?
Electrons always occupy the lowest available energy levels/shells before starting a new one.
This principle helps explain the arrangement of electrons in an atom.
What is the maximum number of electrons in the first main electron shell?
2
The first shell can hold a maximum of 2 electrons.
What are the subshells in the first three main electron shells?
- 1: s
- 2: s, p
- 3: s, p, d
Subshells define the shape and energy levels of electrons within the shells.
How many electrons can each subshell hold?
- s: 2
- p: 6
- d: 10
This distribution is crucial for understanding electron configurations.
What’s an isotope?
A specific nuclear configuration of a given element
Isotopes of the same element have the same number of protons but different numbers of neutrons.
The relative atomic mass of an element is the average mass based on the relative abundance of its known ________.
isotopes
This concept is essential for understanding the mass of elements in the periodic table.
What tool is used to measure the presence and abundance of isotopes in a sample?
Mass spectrometry
Mass spectrometry ionizes atoms and molecules to detect them.
A graph produced by mass spectrometry is known as a ________.
mass spectrum
The mass spectrum displays the relative abundance of each isotope.
Elements are arranged in the periodic table in order of increasing ________.
atomic number
The atomic number indicates the number of protons in the nucleus.
In the periodic table, periods are the ________ and groups are the ________.
rows; columns
Periods indicate the number of electron shells, while groups indicate the number of outer shell electrons.
Elements in the same group have similar ________ and ________ properties.
- physical
- chemical
This similarity is due to having the same number of outer shell electrons.
The periodic table is sorted into blocks based on ________.
electron configuration
The subshell of the outermost electron determines the block.
What is referred to as periodicity in the periodic table?
Repeating and predictable trends
Periodicity includes trends such as atomic radius.
The atomic radius increases as you move ________ a group.
down
This increase occurs because a new electron shell is added with each step down.
The atomic radius decreases as you move ________ a period.
across
This decrease is due to increased attraction between the nucleus and outer shell as protons are added.
