C1 - Atomic Number & Mass Number

What particles are found in the nucleus of an atom?

Protons and neutrons.

What charge do electrons have?

Negative charge.

What charge do protons have?

Positive charge.

What charge do neutrons have?

No charge (neutral).

Why do atoms have no overall charge?

Because the number of electrons equals the number of protons, so positive and negative charges cancel out.

What does the atomic number represent?

The number of protons in an atom.

How can you find the number of electrons in a neutral atom?

It is the same as the number of protons (atomic number).

What does the mass number represent?

The total number of protons and neutrons in an atom.

How do you calculate the number of neutrons in an atom?

Mass number minus atomic number.

How many protons, neutrons, and electrons does lithium have?

3 protons, 4 neutrons, 3 electrons.

If an atom has an atomic number of 4 and a mass number of 9, how many protons, neutrons, and electrons does it have?

4 protons, 5 neutrons, 4 electrons.

What are isotopes?

Atoms of the same element with different numbers of neutrons.

Do isotopes have the same number of protons?

Yes, all isotopes of an element have the same number of protons.

Do isotopes have the same mass number?

No, isotopes have different mass numbers due to different numbers of neutrons.

Give an example of isotopes of carbon and their neutron numbers.

Carbon-12 has 6 neutrons, Carbon-13 has 7 neutrons, Carbon-14 has 8 neutrons.

What is an ion?

An atom that has gained or lost electrons, giving it an overall charge.

Why do positive ions form?

When an atom loses electrons.

Why do negative ions form?

When an atom gains electrons.

How many electrons does a sodium ion (Na⁺) have if its atomic number is 11?

10 electrons.

How many protons, neutrons, and electrons does a sodium ion with 12 neutrons have?

11 protons, 12 neutrons, 10 electrons.

How many electrons does a fluoride ion (F⁻) have if its atomic number is 9?

10 electrons.

How many protons, neutrons, and electrons does a fluoride ion with 10 neutrons have?

9 protons, 10 neutrons, 10 electrons.

How many electrons does an oxide ion (O²⁻) have if its atomic number is 8?

10 electrons.

How many protons, neutrons, and electrons does an oxide ion with 8 neutrons have?

8 protons, 8 neutrons, 10 electrons.

How many electrons does an aluminium ion (Al³⁺) have if its atomic number is 13?

10 electrons.

How many protons, neutrons, and electrons does an aluminium ion with 14 neutrons have?

13 protons, 14 neutrons, 10 electrons.

Why is the number of protons always the same for all atoms of an element?

Because the number of protons defines the element.

Can the number of neutrons vary in atoms of the same element?

Yes, leading to different isotopes.

What effect does gaining or losing electrons have on the overall charge of an atom?

It becomes an ion with a negative charge if electrons are gained, or positive charge if electrons are lost.