Chemistry : Chapter 4 - Chemical formulae and equations

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Chemical symbol

a letter or group of letters representing an element in a chemical formula.

Compound ion

an ion made up of several different atoms covalently bonded together and with an overall charge

Molecular formula

a formula that shows the actual number of atoms of each element present in a molecule of the compound.

Empirical formula

a formula for a compound that shows the simplest ratio of atoms present.

Word equation

a summary of a chemical reaction using the chemical names of the reactants and products.

Reactants

the chemical substances that react together in a chemical reaction.

Products

the substance(s) produced by a chemical reaction.

Balanced chemical equation

the total number of any of the atoms involved is the same on both the reactant and product sides of the equation.

State symbols

symbols used to show the physical state of the reactants and products in a chemical reaction.

Ionic equation

the simplified equation for a reaction involving ionic substances by removing the ions that don’t take part in the reaction.

Formula unit

the unit of an element or compound is the molecule or group of ions defined by the chemical formula of the substance.

Relative molecular mass

the sum of all the relative atomic masses of the atoms present in a molecule.

Relative formula mass

the sum of the all the relative atomic masses of the atoms present in a ‘formula unit’ of a substance.