Atomic Structure

Question 1

What is the atomic number of an element?

Answer 1

The number of protons the element contains

The atomic number identifies elements on the periodic table.

Question 2

What is the mass number of an element?

Answer 2

The number of protons plus the number of neutrons

The mass number provides information about the total number of subatomic particles in the nucleus.

Question 3

Which model of the atom places the orbital electrons into specific energy levels or ‘shells’?

Answer 3

Bohr model

This replaced the ‘planetary’ model proposed by Rutherford

Question 4

How do electrons fill shells in atoms?

Answer 4

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.

Question 5

What is the maximum number of electrons in the first main electron shell?

Answer 5

2

The first shell can hold a maximum of 2 electrons.

Question 6

What are the subshells in the first three main electron shells?

Answer 6

• 1: s
• 2: s, p
• 3: s, p, d

Subshells define the shape and energy levels of electrons within the shells.

Question 7

How many electrons can each subshell hold?

Answer 7

• s: 2
• p: 6
• d: 10

This distribution is crucial for understanding electron configurations.

Question 8

What’s an isotope?

Answer 8

A specific nuclear configuration of a given element

Isotopes of the same element have the same number of protons but different numbers of neutrons.

Question 9

The relative atomic mass of an element is the average mass based on the relative abundance of its known ________.

Answer 9

isotopes

This concept is essential for understanding the mass of elements in the periodic table.

Question 10

What tool is used to measure the presence and abundance of isotopes in a sample?

Answer 10

Mass spectrometry

Mass spectrometry ionizes atoms and molecules to detect them.

Question 11

A graph produced by mass spectrometry is known as a ________.

Answer 11

mass spectrum

The mass spectrum displays the relative abundance of each isotope.

Question 12

Elements are arranged in the periodic table in order of increasing ________.

Answer 12

atomic number

The atomic number indicates the number of protons in the nucleus.

Question 13

In the periodic table, periods are the ________ and groups are the ________.

Answer 13

rows; columns

Periods indicate the number of electron shells, while groups indicate the number of outer shell electrons.

Question 14

Elements in the same group have similar ________ and ________ properties.

Answer 14

• physical
• chemical

This similarity is due to having the same number of outer shell electrons.

Question 15

The periodic table is sorted into blocks based on ________.

Answer 15

electron configuration

The subshell of the outermost electron determines the block.

Question 16

What is referred to as periodicity in the periodic table?

Answer 16

Repeating and predictable trends

Periodicity includes trends such as atomic radius.

Question 17

The atomic radius increases as you move ________ a group.

Answer 17

down

This increase occurs because a new electron shell is added with each step down.

Question 18

The atomic radius decreases as you move ________ a period.

Answer 18

across

This decrease is due to increased attraction between the nucleus and outer shell as protons are added.