Atomic Bonding and Structure

Atoms

Mass Number-Total number of Protons and Neutrons

Atomic Number-Number of Protons

Number of Protons=Number of Electrons

Compounds

Chemically bonded Through a chemical reaction Hard to Separate More than one element

Isotopes

Different atomic forms of the sane element Have the same number of protons But a different number of neutrons They have the same atomic number But a different mass number

Ionic Bonding

Atoms loose or gain electrons All atoms want to be stable (full outer shell) Non metal and a metal Become positive if they lose an electron Become native if they gain one Are now attracted

Structure Ionic compounds always have giant ionic lattices Regular lattice arrangement Held together by strong electrostatic forces between oppositely charged electrons

Properties High melting/boiling points - because of strong forces between- need lots of energy to break conduct electricity when melted- electrons are free to move Dissolve in water easily-can carry an electric current

Ions

If an atom is an ion if it has... lost or gained electrons has the structure of a noble gas the charge is the same as the group number (only for positive) Any positive ions that combine with negative ions form a ionic compound

Formula Ionic compounds are made up of the positively charged and the negatively charged parts The overall charge will always be 0 charges must always balance to 0

Covalent Bonds

Atoms sharing electrons Only share outer electrons only Want to have a full shell-be stable A covalent bond is a pair of Shared electrons Share electrons to create a full outer shell

Structure

Simple Molecular Substances ORGiant covalent Structure

Simple Molecular Substances Small molecules Strong bonds weak forces of attraction between intermolecular forces means low melting/boiling point most are liquids or solids Don't conduct electricity- no ions, no electrical charge

Giant Covalent Structures Similar to giant ionic structures (lattices) No charged electrons Bonded with strong covalent bonds High boiling/melting points

Examples of Giant Covalent StructuresDiamond Each carbon has 4 covalent bonds Very ridged structure Makes it extremely hard Graphite Each carbon forms three covalent bonds Layers that can slide over each other makes it soft and slippery Layers are lose Because of weak intermolecular forces conducts electricity an heat because ach carbon has a delocalised electron Silicon Dioxide (Silica) What sand is made of Each grain of sand is one giant structure Of silicon and oxygen

Metallic Structures

Metals have a giant structure Metallic bonds have 'free electrons' Delocalised electrons come from the outer shell Free to move Reason why they are good conductors of heat and electricity Electrons hold atoms together in regular structure This is because of electrostatic attraction between positive metal ions and negative electrons Layers slide over each other They can be bent and shaped

AlloysHarder than pure metalDifferent elements have different sized atomsWhen metals are mixed the structure is distortedThe layers can no longer slide over each other as easily

Atoms, Compunds and Isotopes

Ionic Bonding

Ions

Covalent Bonding

Metallic Structures