atomic structure and the periodic table

number of protons in the nucleus of an atom

total number of protons and neutrons in the nucleus of an atom

indicate the number of energy levels in an atom of the element

indicate the number of outer shell electrons

• atoms of the same element which have the same proton number but a different nucleon number • similar chemical properties due to same valence • same protons/neutrons but different neutrons • different physical properties due to different mass

• isotopes can be radioactive or stable • if they have extra neutrons they may become unstable • used for cancer treatment, maintaing thickness of material

• unreactive - full outer shells

• contains atoms of different sizes • harder/stronger • resistant to corrosion more

ions are charged particles obtained by the loss or gain of electrons

• cations - lose electrons and become positvely charged

• anions - gain electrons and become negatively charged

• ionic bond formed • metal atom donates 1 electron to nonmetal atom • both become stable and form ions

ions are held together by the electrostatic forces of atraction between them

• giant lattice with crystalline sturcture - regualr arrangement of alternating positive and negatively charged ions

• high melting and boiling points • often solid at room temperature • soluble in water (ion dissociation) • do not conduct electricity when in solid from but do in aqueous or molten form • not volatile

formsbetween nonmetal and nonmetal

• low melting and boiling points • liquids or gases at room temp • usually volatile with aromas • insoluble in water but soluble in organic solvents • cannot conduct electricity • low melting and boiling point due to weak intermolecular forces

diamond and graphite (allotropes of carbon)

• each carbon atom bonded to four other carbon atoms • tetrahedral structure • strong covalent bonds but weak intermolecular forces of attraction • used in jewellry and cutting tools due to hard nature and high melting point

• extremley hard and dense • does not conduct electricity • very high melting point

• each carbon atom bonded to three other carbon atoms • form hexagonal shaped layers with weak intermolecular forces between the layers which allow them to slide over each other • free delocalized electrons between the layers • used as conductors and electrodes for electrolysis because they conduct electricity • used in pencil lead and lubricators because it is soft and slippery

• soft and slippery because layers can slide over each other • high melting point • conducts electricity due to presence of free electrons

• each silicon atom bonded to 4 oxygen atoms while each oxygen atom bonded to 2 silicon atoms • tetrahedral structure • strong covalent bonds • cheap and naturally available as sand

strong electrostatic force of attraction between positive metal ions and delocalised electrons resulting in a giant metallic structure which consists of a regular arrangement of positive metal ions in a sea of free electrons