Formula, Equations And Hazards

Question 1

Formulae

Answer 1

An element is a substance made from atoms with the same number of protons in the nucleus. An atom is the smallest particle of an element that still has its chemical properties.
A molecule consists of two or more atoms chemically bonded together. A compound consists of two or more different elements chemically bonded together.

Question 2

Equations

Answer 2

In a chemical reaction:
- reactants are the substances that undergo a chemical change in a reaction
- products are the new substances formed
Example:
Iron oxide + carbon -> iron + carbon monoxide

Question 3

Ionic equations

Answer 3

An ion is an electrically charged particle. It is formed when an atom, or group of atoms, loses or gains electrons. For example:
Hydrogen atoms and metal atoms lose electrons to form positively charged ions
A positive ion : H+ or Na+
A negative ion : Cl-

Question 4

Hazards, risks and precautions

Answer 4

A hazard is something that could cause:
- damage or harm to someone or something
Some hazard symbols are : harmful, flammable, toxic and corrosive
A precaution is something that you can do to read use the risk of harm from a hazard
Precautions include:
- gloves and eye protection
- protective clothing