Acids and Bases

Acid:
Bronsted-Lowry theory: Proton/ H+ donor
Lewis theory: Electron pair acceptor

Empirical formula calculation

If given % of an element in compound:

1. coefficient = percentage/molar mass
2. If coefficient is halfway between two real values, multiply everything by 2.

Eg: 9.5 x2, 5.5 x2

1.5 understand the terms atom and molecule

Atom is the smallest particle of an element. Consists of neutrons and protons in a nucleus, and electrons orbiting in shells around the nucleus

Eg A structure of an atom


Molecule is two or more atoms that are joined by covalent bonds.


Eg A water molecule consists of two hydrogen atoms and an oxygen atom.

1.3 explain the changes in arrangement, movement and energy of particles during these interconversions

Solid: still; no energy; all particles touching

Add heat v / Remove heat ^

Liquid: Moving to fit space; some energy; all particles touching

Add heat v / Remove heat ^

Gas: Moving freely; lots of energy; particles not touching.

1.2 understand how the interconversions of solids, liquids and gases are achieved and recall the names used for these interconversions

The conversion between solid and gas is called sublimation, but is not needed for the IGCSE.

1.1 understand the arrangement, movement and energy of the particles in each of the three states of matter: solid, liquid and gas

Solid: particles are arranged in a lattice structure, tightly packed and no free spaces between each particle, do not move, can only vibrate.

Liquid: particles are randomly arranged, close together, with little space bewteen them and collide frequently.

Gas: particles are far apart and at random, move quickly, high energy in all and random directions.