- The periodic table is made up of about 100 elements.
- An element is a substance made up of only one type of atom.
- Atoms are the simplest particle substances can be broken down into.
- On the periodic diagram the metals are on the left hand side and non-metals are on the right hand side of a dividing line.
- The first group contains the alkali metals - most reactive metals. This group contains lithium, sodium, potassium, rubisium and caesium.
- The transition metals are the most common metals.
- Group 7 contains halogens like fluorine, chlorine, bromine and iodine.
- Group 0 contains noble gases like helium, neon, argon and krypton. They are very unreactive.
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- The three types of chemical reactions are ionic bonding, covalent bonding and metallic bonding.
- Word reactions show what chemicals are reacted to get a product.
- Sodium + Water ==> Sodium Hydroxide + Hydrogen
- An arrow is used instead of an equals sign because the chemicals before and after the reaction are changed.
- The chemicals on the left are reactants while the chemicals on the right are products.
- Chemical symbols can also be used to show this reaction.
- 2Na[s] + 2H₂O[l] ==> 2NaOH[aq] + H₂[g]
- The state symbols tell us what state each chemical is in ('aq' stands for aqueous or dissolved in water).
- Chemical reactions are balanced to ensure the same number of atoms is found on each side of the equation. This is because of the law of conservation of mass - atoms are neither created nor destroyed.
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