Science exam year 9 (chem + earth and space) edit 1

Group 1

Alkali metals

Group 2

Alkaline earth metals

Group 3-12

Transition metals

Group 17

Halogens

Group 18

Noble gases

Charge of a proton

+1

Charge of a neutron

0

Charge of an electron

-1

Valence shell

Outermost electron shell

Isotope

Atoms of the same element that have different numbers of neutrons

Electron configuration

2,8,8,2

Group 1 reactivity pattern

Further down the group = more reactive

Group 1 properties

Soft, low density, dull

Group 2 reactivity

Reacts steadily with water

Group 2 properties

Harder, denser, higher melting points than group 1

Magnetic metals

Iron, cobalt, nickel

Metalloids

Mix of metals and non-metals; shiny and can form alloys, brittle and poor conductors

Halogens reactivity pattern

Further down the group = less reactive

Noble gas reactivity

Non reactive (8 electrons in the valence shell)

Ion

An atom that has gained or lost electrons to become stable

Cation

Positively charged ion (lost electrons)

Anion

Negatively charged ion (gained electrons)

Ionic bonding

Transfer of electrons from a metal to a non-metal

Covalent bonds

When 2 non-metals share one or more electrons to achieve a full valence shell

Chemical equation

reactants -> products

Signs of a chemical equation

Gas produced, colour change, precipitate (solid) formed, energy change

Metal and water reactions

Metal + water -> metal hydroxide + hydrogen

Metal and acid reactions

Metal + acid -> salt + hydrogen

Hydrogen test

Squeaky pop test

Decomposition reactions

AB -> A + B

Balancing equations

Equal number of atoms on both sides - place numbers in front of symbols

Rusting equation

Iron + Oxygen -> Iron (III) Oxide

Accelerating factors of rusting

Salt water and acid rain

Prevention of rust

Barrier methods, galvanising, sacrificial anodes

Barrier methods

Excludes reactants

Galvanising

Dipping iron into a layer of zinc - mix of barrier and sacrificial methods

Sacrificial anodes

Placing a more reactive substance near the iron as a sacrifice to corrode in place of the iron

4 spheres

Lithosphere, hydrosphere, atmosphere, biosphere

Lithosphere

Earth's brittle outer crust and uppermost solid mantle

Hydrosphere

All the water found on Earth. Regulates temperatures and shapes landforms through erosion

Atmosphere

Protective mixture of gases bound to Earth through gravity. Shields Earth from solar radiation and moderates surface temperatures

Biosphere

All living organisms on Earth

Water cycle

Water body, evaporation, transpiration, condensation, precipitation, run-off, groundwater

Photosynthesis equation

Carbon dioxide + water -> glucose + oxygen

Combustion equation

Hydrocarbon + oxygen -> carbon dioxide + water

Fossil fuels

Coal, oil, and natural gas formed from the compacting of dead organic materials deep underground

Factors of the carbon cycle

Photosynthesis, respiration, decomposition, fossil fuels, combustion, feeding, death and waste

Ocean acidification

When CO2 dissolves in seawater, it creates a more acidic pH