Chemistry - unit 1

• Rate = Change in property / Change in time
• There are 7 Diatomic elements:

- Hydrogen  - Nitrogen  - Oxygen - Fluorine - Chlorine - Iodine - Bromine

• Proton has a charge of 1+ and its relative mass is 1
• Neutron has a charge of 0 and its relative mass is 1
• Electron has a chage of -1 and its relative mass is almost 0
• The atomic number is proton = electrons (only in a neutral atom)
• The mass number is the number of protons + the number of neutrons 
• The top number in an nuclide symbol is the mass number and the bottom is the atomic number.
• Isotope are atoms that have the same atomic number but a different mass number
• All metals are + 
• All non metals are -
• ionic bonding is between non metals and metals 
• Ionic bondingoccurs when electrons are transferred from one atom to another atoms
• The ionic bond is formed so that both the metal and the non metal become more stable.
• Ionic lattice is when a solid ionic compounds arrange themsevles into alttices becase of the attraction of opposite charges
• Covalent bonds are formed by atoms SHARING electrons.  They are formed when non metals bond together.
• All the 7 diatomic elements are bonded covalently 
• covalent network is like all bonds between normal covalent bonds but the huge network structure gives the substance its strength.
• Diamond - all 4 electrons are held in a strong covalent bond
• Graphite - 3 electrons are held in strong covalent bonds forming layer. the 4th electron is delocalized.
• Covalent bonds tend to have low melting points.  This is because to melt the covalnet substance, the molecules merely need to be separated from each other. 
• There are only weak intermolecular forces keeping the molucles together.
• Ionic compounds have high melting points.  This is because the ionic bonds have to be broken down in order to melt it, which willrequire a lot of energy.
• Diamond has…