Chemical equations/ Structure of the atom

Question 1

Explain why mass can only be conserved in a chemical reaction. (conservation of Mass)

Answer 1

Mass can only be conserved because matter can not be created or destroyed, only transformed.

Question 2

Justify in detail how mass may appear to change in a chemical reaction.

Answer 2

• gas production or loss
• Gas absorption
• Evaporation or condensation
• Measurement and observation errors
• Incomplete reaction or reversible reactions

Question 3

What does ‘aq’ mean in a chemical reaction.

Answer 3

It means the substance dissolved in water.

Question 4

State the relative charges and masses of subatomic particles.

Answer 4

Protons:
- Have a positive charge (+1)
- Relative mass of 1
- Found in the nucleus, contributing to most of the atoms mass.

Neutrons:
- Have no charge (0) and are electrically neutral.
- Relative mass is 1
- Found in the nucleus, providing stability to the atom by reducing repulsion between protons.

Electrons:
- Have a negative charge (-1)
- Relative mass is negligible
- Found in the atom’s energy levels (shells)

Question 5

What charge do atoms have?

Answer 5

Atoms have no overall charge. (They are neutral)

Question 6

Why do atoms have no overall charge?

Answer 6

Atoms have no overall charge because the number of protons (positively charged particles) in the nucleus is equal to the number of electrons (negatively charged particles) surrounding the nucleus. These charges cancel each other out, resulting in a net charge of zero.