1.5 Symbols, Formulae and Equations

Water

H₂O

Carbon dioxide

CO₂

Carbon monoxide

CO

Sulfur dioxide

SO₂

Ammonia

NH₃

Methane

CH₄

Hydrochloric acid

HCl

Sulfuric acid

H₂SO₄

Nitric acid

HNO₃

Metal + oxygen

Metal oxide

Metal + cold water

metal hydroxide + hydrogen

metal + steam

metal oxide + hydrogen

metal + acid

salt + hydrogen

base + acid

salt + water

metal carbonate + acid

salt + water + carbon dioxide

metal carbonate ——>(heat)

metal oxide + carbon dioxide

hydrocarbon fuel + oxygen

carbon dioxide + water

Atom

Smallest part of an element

Element

A pure substance made of only one kind of atom that cannot be broken down further

Compound

substance made up of atoms of two or more different elements joined by chemical bonds

Mixture

combination of two or more different substances that are not joined by chemical bonds

Chemical symbol

A one or two letter representation of an element

Number of elements

118

Chemical reaction

the formation of a new chemical substance

Periodic table

A chart of the elements showing the repeating pattern of their properties

Property

A description of a substance

Molecule

A group of atoms bonded together

Separation of compounds

Requires a chemical reaction to break the bonds between atoms.

Formula of an element

Has a single capital letter

Formula of a compound

Has more than one capital letter, and tells you the ratio of the elements in a compound

Chemical reaction

Rearranging atoms to make new chemicals

Conservation of mass

Matter is not created or destroyed during a chemical reaction

Mass of products =

The mass of the reactants

Balanced symbol equation

symbol equation in which there are equal numbers of each type of atom on either side of the equation

Reason mass decreases in a reaction

A new gas is formed

Reason mass increases in a reaction

A reactant is a gas

Coefficient

Big numbers in front of formulae which multiply a formula 2NaCl

Word equation

An equation in which the reactants and products in a chemical reaction are represented by words

Reactant

A starting material in a chemical reaction

Products

The new substance produced by a chemical reaction.

H

Hydrogen

He

Helium

Fe

Iron

N

Nitrogen

Na

Sodium

F

Fluorine

Li

Lithium

C

Carbon

CO2

Carbon dioxide

O

Oxygen

Mg

Magnesium

Al

Aluminum

K

Potassium

KF

Potassium fluoride

Ca

Calcium

CaF₂

Calcium fluoride

CaSO₄

Calcium sulfate

Sodium nitrate

NaNO₃

CaS

Calcium sulfide

Na₃N

Sodium nitride

Diatomic elements

H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂