describe the structure of an atom in term of a central nucleus, containing protons and neutrons, and 'shell' of electron

describe the build-up of electrons in 'shells' and understand the significance of the noble gas electronic structures and of the outer shell electrons

state the change and approximate relative masses of protons in the nucleus of an atom

define and use nucleon number as the total number of protons and neutrons in the nucleus of an atom

define and use proton number as the number of protons in the nucleus of an atom

use protons number and simple structure of atoms to explain the basis of the periodic table, with social reference to the element of proton numbers number 1 ~ 20

define isotopes as atoms of the same element which have the same proton number but a different nucleon number

state that there are several different forms of carbon, including diamond and graphite

state that non-metaillic element form simple molecules with covalent bonds between atoms

describe the formation of single covalent bonds in H2 Cl2 H2O CH4 NH3 and HCI as the sharing of pairs of electrons leading to the use of dot-and-cross diagrams

describe the differences in volatility, solubility and electrical conductivity between ionic and covalent compounds

use dot-and-cross diagrams to describe the formation of ionic bonds between group i and group VII