Atoms

Question 1

What do atoms consist of?

Answer 1

Atoms consist of electrons surrounding a nucleus that contains protons and neutrons.

Question 2

What is the electrical charge of neutrons, protons and electrons?

Answer 2

Neutrons are neutral, but protons and electrons are electrically charged: protons have a relative charge of +1 and electrons have a relative charge of -1.

Question 3

What are atoms?

Answer 3

All substances are made of tiny particles called atoms. An element is a substance that is made of only one sort of atom.

Question 4

How is the Periodic Table arranged?

Answer 4

The horizontal rows in the periodic table are called periods and the vertical columns are called groups.
The metals are shown on the left of the periodic table, and the non-metals are shown on the right.

Question 5

What are the properties of an atom?

Answer 5

An atom has a small central nucleus made up of smaller sub-atomic particles called protons and neutrons. The nucleus is surrounded by even smaller sub-atomic particles called electrons.

Question 6

What is significant about the protons and electrons in an atom?

Answer 6

The number of electrons in an atom is equal to the number of protons in its nucleus. This means atoms have no overall electrical charge.

Question 7

What is the atomic number of an atom?

Answer 7

The atomic number of an atom is the number of protons it contains. It is also the bottom number in the chemical symbol on the periodic table.

Question 8

What is the mass number of an atom?

Answer 8

The mass number of an atom is the total number of protons and neutrons it contains. The mass number of an atom is never smaller than the atomic number. It can be the same, but is usually bigger.

Question 9

What will you never find in the periodic table?

Answer 9

You will never find a compound in the periodic table, because these consist of two or more different elements joined together by chemical bonds.

Question 10

What are the Group 1 (the first column on the periodic table) elements called in the periodic table?

Answer 10

The alkali metals. They are called this because they form alkaline compounds.

Question 11

What are the Group 0 (the last column in the periodic table) elements called in the periodic table?

Answer 11

The noble gases. They are called this because they are very unreactive.

Question 12

What happens when elements react?

Answer 12

When elements react, their atoms join with other atoms to form compounds.

Question 13

What happens when chemical bonds form?

Answer 13

Atoms transfer and share electrons.

Question 14

What is ionic bonding?

Answer 14

Ions are charged particles that form when atoms (or clusters of atoms) lose or gain electrons:
Metal atoms lose electrons to form positively charged ions.
Non-metal atoms gain electrons to form negatively charged ions.

Question 15

What is covalent bonding?

Answer 15

The atoms in a molecule are joined together by covalent bonds. These bonds form when atoms share pairs of electrons.

Question 16

What is a chemical formula?

Answer 16

The chemical formula of a compound shows how many of each type of atom join together to make the units which make up the compound.

Question 17

Unbalanced and Balanced equations

Answer 17

Here is an unbalanced equation:

Cu + O2 → CuO

Here is the balanced symbol equation:

2Cu + O2 → 2CuO

Question 18

One rule for balancing equations.

Answer 18

Never change a formula to balance an equation.

Question 19

What happens to the mass of an atom before and after a chemical reaction?

Answer 19

No atoms are lost or made during a chemical reaction. This means that the mass is always conserved. In other words, the total mass of products after the reaction is the same as the total mass of the reactants at the start.