Structure and Bonding - AQA Additional Chemistry

Structure

• The nucleus of an atom contains - Protons (with a charge of +1) and Nuetrons (with a charge of 0)
• Electrons (with a charge of -1) orbit the nucleus

Atomic Number

• Number of protons present in the nucleus
• The elements are arranged in order of the atomic numbers in the periodic table
• The number of protons = The number of electrons

• Electrons are in energy levels that can be reprsented as 'shells'
• Electrons in the lowest energy level are closest to the nucleus
• Electrons occupy the lowest energy level first with 2 electrons, the other levels contain 8 electrons
• All elements in a group of the periodic table have the same number of outer electrons

• Compounds are substances which a chemically combined
• When elements react the atoms form a stable arragement of electrons
• Atoms can gain or lose electrons to form ionic bonds
• Atoms share electrons to form covalent bonds

• Electrons are gained or taken by atoms to from ions
• Compound made of ions form very regular giant structures
• Strong forces of attraction form a lattice which hole the ions together

• When 2 atoms share a pair of electrons a covalent bond is formed
• The number of bonds formed depends on the number of electrons an atom needs to forms a stable electron arangment
• mst covalent bonded substances consist of small molecules, but some have giant structures

• Metals have giant structures of layers of atoms arranged in a regular patten
• (Higher) The electrons in the outer shell delocalise resulting in strong electrostatic forces between these electrons and the positively charged metal ions