3.1.1

• the periodic table is arranged by increasing atomic number and so positive nucleus charge
• groups show the number of electrons in the outer shell
• periods show the number of shells
• as you go along the periodic table the size of the atom decreases as the electrons are pulled in by the strong positive charge
• periodicity: shows the repeating trends in physical and chemical properties
• ancient philosophers like Aristotle believed there were 4 elements water, air, earth and fire. these are similar to current states of matter
• Lavoisier wrote the first chemical textbook with elements that he believed could not be broken down any further however it contained some compounds and mixtures. it also included how to form compounds and distinguished metals and non metals
• Berzelius arranged elements by atomic weight and determined the composition of compounds by mass. he introduced the lettering symbols for elements
• Dobereiner created dobereiner triads for elements with similar characteristics
• newlands arranged elements in order of mass and created the law of octaves where every 8th element was similar
• Mendeleev arranged elements by atomic mass and left gaps as well as predicting the properties of undiscovered elements
• Moseley arranged elements by atomic number and created the modern periodic table. since then man made elements have been created and added
• the number of electrons in a shell = 2 x the shell number ^2
• periods 2 and 3 contain shell levels 2 and 3
• metalloid: an elements with properties of a non-metal and a metal
• orbitals are represented by boxes, when drawing an electron use a single head arrow to represent 1 electron
• metals fill up the s orbital
• transition metals fill up the d orbital
• non metals fill up the p orbital
• electrons fill the lowest energy level first
• orbitals with the same energy fill singularly first then doubly to prevent repulsion
• once 3d is filled it falls below 4s
• it is harder to remove electrons from sub shells the more you remove them as the positive charge from the nucleus stays the same
• zinc is unlike a transition metal as it looses 4s electrons unlike d-block transition metals
• orbitals contain up to 2 electrons
• giant covalent lattices are also known as macromolecules
• allotropes: different forms of an element in the same state
• carbon forms many allotropes of giant covalent lattices
• diamond is a giant covalent structure made of carbon atoms with 4 carbon carbon bonds. it has a high melting point, is extremely hard, a good thermal conductor due to movement of vibrations but cannot dissolve or conduct electricity
• silicon forms the same structure as diamonds
• graphite is hexagonal rings of carbon with 3 carbon - carbon bonds joined in layers by weak London forces. the layers can slide and the delocalised electrons can conduct electricity, its less dense than diamond and has a high melting point as well as being insoluble as the covalent bonds are too strong to break
• graphite is used as a dry lubricant and in sport equipment
• graphene is a layer of graphite
• graphene is the best known electrical conductor, extremely strong and light and transparent
• graphene is used in aircrafts, electronics and touchscreens
• metals form a giant metallic lattice
• giant metallic lattice : cations are electrostatically attracted to negative delocalised electrons
• the number of delocalised electrons in a giant metallic lattice affect the boiling point. the more electrons delocalised the strong the bonds the higher the melting point
• the size of the ionic radius affect a giant metallic lattices melting point. the smaller the ionic radius the stronger the nuclear charge exposed the more attracted the electrons the stronger the bonds the higher the melting point
• metal ions in a metallic structure can slide past one another making it ductile and malleable