Atomic Bonding, Structures and Nanoparticles

• The Plum Pudding model, was discovered by Thomson, discovered the electron and consists of a positively charged sphere with negatively charged electrons throughout.
• Rutherford‘s model, proved Thomson’s wrong. In the new model the Positive Charge is concentrated in the nucleas, surrounded by Orbiting electrons in electron shells.
• Proton: Charge: One+ Mass: One

  Electron: Charge: One- Mass: 1/2000

  Neutron: Charge: Zero Mass: One
• Mixture: Substance that is not chemically joined, separated easily
• Compound: pure substance of 2 or more elements chemically joined
• Element: Pure substance, 1 type of atom. Cannot be broken down into anything simpler
• Atom: The smallest particle of an element that can exist, and take part in chemical reactions
• Period: horizontal row in the periodic table
• Group: vertical column in the periodic table
• Isotope: Same number of electrons, different number of nuetrons
• Ions: An atom that has gained or lost an electron.

  Cation +

  Anion -
• Radius of an atom is 0.1 Nanometres
• 1 Nanometre is 1x10^-9 metres
• Relative atomic mass: Weighted mean mass of an atom, taking each isotope into account.
• Ionic Bonding:

  Occurs in compounds with a metal+non-metal.

  Metal (Form Cation) loses E- and Non Metal Gains E- (Form Anion).

  Ionic Bonds: Large Lattices
• Covalent Bonds:

  Two or more non-metal atoms sharing a pair of electrons.
• Molecule:

  Two or more atoms covalently bonded together.
• Metallic Bonding:

  Attraction between positive metal cations and delocalised electrons.

  Delocalised E- are free to move throughout the whole structure.
• Giant Ionic Lattice:

  3-D structure of oppositely charged ions, held together by ionic bonds.

  High mtp- A-lot of energy to break ionic bonds.

  Soluble in water- most ionic compounds form aqueous solutions.

  Good Conductors when Molten/Dissolved- When dissolved ions can move and carry charge.
• Aqueous Solution:

  solution which is solvent in water.
• Molecular Covalent Structures:

  Within each molecule there are strong covalent bonds, molecules held together with weak van der waals forces of attraction.
• Molecular Covalent:

  Low Mtp/Bp- Little energy needed to break van-der-waals.

  Doesn't Conduct-

  Molecules are neutral, no charged particles to carry charge.

  Insoluble in Water-

  Many single covalent molecular substances have low solubility/ insoluble
• Allotropes: Different forms of the same element, in the same state.
• Metallic bonding: Electrons delocalised over all metal atoms, creating sea of electrons between layers of positive nuclei. Strong electrostatic force of attraction between positively charged nucleus and negatively charged electron cloud. Metals conduct electricity because free electrons can flow through lattice.
• Giant Covalent Structure: Three dimensional structure of atoms that are joined by covalent bonds
• Diamond:

  Each C atom covalently bonded to 4 others

  Very hard 3-D tetrahedral structure

  High Mtp/Bp- Many Strong covalent bonds

  Doesn't conduct- no free ions or electrons to move and carry charge

  Diamond Tipped Tools- used to cut metals, glass, hard rock
• Period indicates Number of shells in use
• Group indicates number of electrons in the outer shell