Formula and equations

Explain how to write the names of ionic compounds (ionic compounds are named by…)

Ionic compounds are named by writing the metal ion first followed by the non‑metal with an –ide ending

Describe how to write the formula of an ionic compound (the formula is written by…)

The formula is written by balancing the charges of the ions so the overall charge is zero

Explain how to identify the charge on common ions (the charge can be found because…)

The charge can be found because group number shows electrons lost or gained

Describe how to name covalent compounds (covalent compounds are named by…)

Covalent compounds are named by using prefixes to show the number of each atom

Explain the meaning of prefixes in covalent compounds (prefixes such as di‑ and tri‑ mean…)

Prefixes such as di‑ and tri‑ mean the number of atoms present in the molecule

Describe what a word equation shows (a word equation shows…)

A word equation shows the reactants and products written in words

Explain how to convert a word equation into a symbol equation (you convert it by…)

You convert it by replacing each substance with its correct chemical formula

Describe why equations must be balanced (equations must be balanced because…)

Equations must be balanced because atoms cannot be created or destroyed

Explain the law of conservation of mass (the law states that…)

The law states that the total mass of reactants equals the total mass of products

Describe how to balance a symbol equation (you balance it by…)

You balance it by adjusting coefficients so the number of atoms of each element is equal on both sides

Explain why subscripts cannot be changed when balancing (subscripts cannot be changed because…)

Subscripts cannot be changed because they alter the identity of the substance

Describe what state symbols show (state symbols show…)

State symbols show the physical state of each substance in a reaction

Explain the meaning of (s) in equations (s means…)

(s) means the substance is a solid

Explain the meaning of (l) in equations (l means…)

(l) means the substance is a liquid

Explain the meaning of (g) in equations (g means…)

(g) means the substance is a gas

Explain the meaning of (aq) in equations (aq means…)

(aq) means the substance is dissolved in water

Describe how to check conservation of mass in a reaction (you check it by…)

You check it by comparing the total mass of reactants and products to ensure they are equal

Explain why mass may appear to change in reactions involving gases (mass appears to change because…)

Mass appears to change because gases may escape or enter the reaction vessel

Describe how to convert a word equation into a balanced equation (you do this by…)

You do this by writing formulae, adding state symbols, and balancing atoms using coefficients