2026S2 Chapter 11 Chemical Changes (Chemistry)

WA2 revision

HCl

Chemical formula of hydrochloric acid

A subatomic particle that has no charge and that is found in the nucleus of an atom.

Definition of a neutron

NH3

Chemical formula of ammonia

CH4

Chemical formula of methane

C6H12O6

Chemical formula of glucose

AgCl

Chemical formula of silver chloride

Chemical formula of carbon dioxide

CO2

Acid + alkali

salt + water (neutralisation)

Acid + reactive metal

salt + hydrogen gas (effervescence observed, metal shrinks)

Use a lighted splint: will extinguish with a ‘pop’ sound in the presence of hydrogen

Test for hydrogen

salt + water + carbon dioxide (effervescence observed, solid dissolves in acid)

Acid + metal carbonate

Bubble gas into limewater - white precipitate will form in the presence of carbon dioxide.

Test for CO2

when a substance is heated or burnt in the presence of oxygen to form one or more new substances.

Definition of combustion

when a substance breaks down into two or more simpler substances upon heating.

Definition of thermal decomposition

Atoms of the same element with the same proton number but different number of neutrons.

Definition of an isotope

Definition of a proton

Positive (+) charge - located in the nucleus

negatively charged particle located in the shell of an atom

Definition of an electron

They have a fully filled valence shell.

What makes group 0 atoms stable and very unreactive?