Core Definitions and Core Knowledge - AS level

A repeated pattern or trend

The relative atomic mass of an element is the average mass of its atoms, compared to 1/12th the mass of a carbon-12 atom

formula for a family of compounds. E.g. alkanes‡ CnH2n+2 where n is the number of carbon atoms

shows the ratio of atoms in a compound. It is the simplest ratio in which atoms combine to form a compound

tells us how many of each type of atom there are in each molecule of the compound

all the hydrogen atoms are removed from carbon chains, leaving just a carbon skeleton with functional groups attached to it

shows all the bonds in the molecule as individual lines (each line represents a pair of shared electrons)

shows how the various atoms are bonded

A crystalline compound containing water molecules

A substance containing no water molecules

The water molecules bonded into a crystalline structure of a compound

• Use a mass balance that calculates to a greater number of decimal places to get a more accurate mass reading • Heat mixture until you record a constant mass

• Anhydrous solid mass at end will be less than it should be - You could heat it more gently, or take mixture off of heat

The energy required to remove one electron from each atom in one mole of gaseous atoms to produce one mole gaseous 1+ ions

The energy required to remove one electron from each 1+ ion in one mole of gaseous 1+ ions to produce one mole of gaseous 2+ ions

Number of protons in the nucleus

A region within an atom that can hold up to two electrons with opposite spin

• As many particles as there are carbon atoms in 12g of carbon - 12 • Or: 6.02x10^23 atoms

-there is an uneven distribution of electrons present in molecule ↳ this creates an instantaneous dipole -these cause induced dipoles in neighbouring molecules

H

A substance that oxidises another substance by attracting its electrons and becoming reduced in the reaction itself(absorbs electrons from other substances)

A substance that reduces another substance in a reaction but becomes oxidised in the reaction itself(loses electrons, donates them)

The electrostatic attraction between between cations and delocalised electrons

The electrostatic attraction between two atomic nuclei and a shared pair of electrons