Chapter 8: Atoms and Molecules Electronic Configuration and Isotopes

Question 1

Define ‘atom’

Answer 1

It is the simplest unit of an element.

Question 2

What are the 3 subatomic particles?

Answer 2

Protons, neutrons and electrons

Question 3

What are the relative masses of the subatomic particles?

Answer 3

Protons: 1u
Neutrons: 1u
Electrons: negligible (or 1/1836)

Question 4

In the periodic table, which number represents the amount of protons in that element?

Answer 4

Top number

Question 5

In the periodic table, which number represents the number of neutrons + protons in that element?

Answer 5

Bottom number

Question 6

What is the ‘top number’ of an element known as?

Answer 6

Proton/ Atomic number

Question 7

What is the ‘bottom number’ known as?

Answer 7

Mass/ Nucleon number

Question 8

How are the elements in the periodic table arranged?

Answer 8

They are arranged in ascending order of proton number.

Question 9

Why are atoms electrically neutral?

Answer 9

The number of negatively charged neutrons are equal to the number of positively charged protons. Thus they cancel out each other.

Question 10

What is a characteristic of an ion?

Answer 10

The number of electrons and the number of protons are not equal.

Question 10

How many electrons can each electron shell take?

Answer 10

1st shell: 2
2nd shell onwards: 8

Question 10

How do you find out how many electron shells there are?

Answer 10

You can look at the element’s period number.

Question 10

What does ‘valence’ mean?

Answer 10

Outermost.

Question 10

What does the number of valence electrons tell you about an element?

Answer 10

Its group number, chemical reactivity

Question 11

What is so special about Group 18 of the periodic table?

Answer 11

They are noble gases, meaning that they are non-reactive.

Question 11

Why are the elements in Group 18 non-reactive?

Answer 11

They have a fully filled valence shell, meaning that they do not need to lose or gain electrons ; they are stable.

Question 11

Define ‘isotopes’

Answer 11

Isotopes are atoms of the same element with the same number of protons but different number of neutrons.

Question 11

What are the characteristics of isotopes?

Answer 11

1. They have the same chemical properties
2. They have different physical properties (e.g. boiling point, density)

Question 12

Define ‘molecule’.

Answer 12

It is a substance formed when two or more atoms are chemically combined (reaction) together.

Question 12

What is the characteristic of a molecule of an element?

Answer 12

The molecules are made up of the same type of atoms.

Question 13

What is the characteristic of a molecule of a compound?

Answer 13

The molecules are made up of different types of atoms.

Question 14

Can Group 18 elements form a molecule? Why?

Answer 14

No, since they are unreactive, they are unable to react with any other atoms to form a molecule, thus they will always exist as an atom.

Question 15

What do you need to do if you have 3 or more valence shells and the number of valence electrons are more than 3?

Answer 15

You have to add 10 to the number of valence electrons to get the group number of that element.