GCSE Chemistry Atomic Structure And Periodic Table

What is the atomic number of an atom?

The number of protons in the nucleus (also equal to the number of electrons in a neutral atom)

What is the mass number of an atom?

The total number of protons + neutrons in the nucleus

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

Mass number − Atomic number

What are isotopes?

Atoms of the same element (same number of protons) that have different numbers of neutrons

What is the relative charge of a proton?

+1

What is the relative charge of a neutron?

1

What is the relative charge of an electron?

−1

What is the relative mass of a proton?

1

What is the relative mass of an electron?

Very small (approximately 1/1836 or negligible)

Where are protons and neutrons found?

In the nucleus of the atom

Where are electrons found?

In shells (energy levels) around the nucleus

How are electrons arranged in shells?

First shell holds up to 2 electrons; second shell holds up to 8; third shell holds up to 8 (for GCSE)

What does the electronic structure of an atom tell us?

How the electrons are arranged in shells (e.g. sodium is 2,8,1)

What is a group in the periodic table?

A vertical column of elements that have the same number of electrons in their outer shell

What is a period in the periodic table?

A horizontal row of elements; the period number equals the number of electron shells

What does the group number tell you about an element?

The number of electrons in the outer shell (for groups 1–7)

What does the period number tell you about an element?

The number of electron shells the atom has

Where are metals found in the periodic table?

On the left and in the middle (majority of the table)

Where are non-metals found in the periodic table?

On the right-hand side

What are the Group 1 elements called?

Alkali metals

Give three properties of the alkali metals

Soft, low density, react vigorously with water to produce hydrogen and an alkaline solution

What happens to the reactivity of alkali metals as you go down the group?

Reactivity increases (outer electron is further from the nucleus and more easily lost)

What are the Group 7 elements called?

Halogens

Give three properties of the halogens

Non-metals, coloured, form molecules of two atoms (diatomic)

What happens to the reactivity of the halogens as you go down the group?

Reactivity decreases (harder to gain an electron as the outer shell is further from the nucleus)

What are the Group 0 elements called?

Noble gases

Why are the noble gases unreactive?

They have a full outer shell of electrons (stable electronic structure)

What is the trend in melting/boiling points of the noble gases down the group?

Melting and boiling points increase (atoms get larger, stronger intermolecular forces)

How is the modern periodic table arranged?

By increasing atomic number (and elements with similar properties are in the same group)