Chemistry - Year 8 Atoms and Periodic Elements

Element

One kind of atom that can not be broken down into smaller substances

Mixture

Two or more elements that are not chemically bonded and can contain elements and compounds

Compound

Two or more elements that are chemically bonded together

Periodic Table

An arrangement of all known elements organised into periods and groups

Elements of the Periodic Table

Each element has a symbol, an atomic number and an atomic mass

Atomic number

Amount of protons present that, if a stable atom, is equal to the amount of electrons

Atomic mass

The total number of protons and neutrons in the atom and the atomic mass - the atomic number is the amount of neutrons

Group 1 of the periodic table

Alkali Metals

Group 2 of the periodic table

Alkali Earth Metals

Group 7 of the periodic table

Halogens

Group 0/8 of the periodic table

Noble Gases

Mid table section

Transition Metals

Properties of metals

Shiny, Solid (except mercury) at room temp, High density, Strong, Malleable (can bend without breaking), Good conduction of heat and electricity, Iron, cobalt and nickel are magnetic

Properties of non-metals

Dull, circa half half gases and solids bromine being liquid, Low density, Weak, Brittle, poor conductors of heat and electricity except graphite for electricity, No magnetic materials.

Properties of compounds

Compounds have different qualities to the elements they were formed from like iron sulfide is not magnetic unlike iron

Rule 1 of compound naming

If two or more elements are combined, the name usually ends in -ide e.g. iron sulfide. The metal comes first and then the non-metal

Rule 2 of compound naming

If three or more different elements are combined with one of them being oxygen, the name usually ends in -ate e.g. calcium carbonate is calcium + carbon + oxygen

Stages of copper extraction from malachite (Copper Carbonate or CuCO₃)

1. Heat up the copper carbonate to remove carbon dioxide to leave copper oxide, CO₂

2. Heat it up again with carbon to remove the oxygen producing copper and carbon dioxide.

Both tests for carbon dioxide.

Limewater in a test tube with the substance in, positive test is the limewater turns cloudy. Bicarbonate indicator into a test tube containing it and positive test is that it turns from red to yellow

Test for Water

Anhydrous copper sulfate crystals. Positive = white to blue

Test for Hydogen

Hold a lit splint over the tube. Positive = squeaky pop

Test for oxygen

Glowing splint in tube = relit is a positive test

_Acids

Chemical opposite of alkalis, taste sour and can be corrosive

Alkalis

Chemical opposites of acids, feel soapy, can be corrosive

Blue litmus paper

Turns red when in touch of an acid

Red litmus paper

Turns blue when in touch with alkalis. If neither litmus paper changes colour, It is a neutral substance.

Universal Indicator

Probably better than Litmus paper because it shows a scale of the strength of the acid or alkali.

Neutralisation

When an acid and alkali mix, they cancel each other out to make a more neutral substance and as they do this, produce water and a salt. This is how antacids work.

Reactions of metals and acids

When a metal and an acid react, they have different reactivities based on the different metals and strength of acids and when they react, form a salt and hydrogen gas

Order of reactivity

The letters are PSLCMZIC which can form the mnemonic Pokémon’s Strongest League Conquered Matches; Zygarde Interfered and Crushed (Pokémon themed) or Potassium, Sodium, Lithium, Calcium, Magnesium, Zinc, Iron, Copper

Metal reaction with hydrochloric acid

The salt produced ends in chloride + hydrogen

Metal Reaction with sulfuric acid

The salt produced ends in sulfate + hydrogen