C1 Atomic structure

C1 Atomic structure

1.1 Atoms
1. Each element is made of one type of atom.
2. Elements are arranged in groups, called columns.
  1. These groups have similar properties.
3. Atoms have a nucleus that is surrounded by electrons.
4. When elements react compounds are formed.
  1. Compounds have two or more elements in them, that have combined together.
1.2 Chemical equations
1. Reactants are what you start off with.
2. Products are what you are left with.
3. Atoms are neither created of destroyed (conservation of mass law).
  1. This states no atoms are made or lost in a chemical reaction.
    1. In some reactions it looks like it appears to change, but this is normally just when gas is a product.
4. Equations must always be balanced.
5. Must also have state symbols.
  1. (s) solids, (l) liquids, (g) gases, (aq) aqueous solutions, can be dissolved in water.
1.3 Separating mixtures
1. A mixture is made up of two or more substances, that aren't chemically bonded.
  1. The chemical properties of each substance in the mixture are unchanged.
2. Mixtures are only separated in physical processes.
  1. Filtration: separates insoluble and soluble in a solvent. E.g. Separates sand and salt from a salt solution.
  2. Crystallisation: separates a soluble solid from a solvent. E.g. Sodium chloride from a salt solution.
  3. Distillation: separates a solvent from a soluble solid dissolved in the solvent. E.g. Seawater is distilled to obtain usable water.
1.4 Fractional distillation and paper chromatography
1. Fractional distillation
  1. Separates mixtures of miscible liquids. E.g. Ethanol and water.
  2. The liquid with the lowest boiling point is collected first.
  3. To aid the separation, add a fractional column. E.g. separated ethanol from a fermented mixture.
2. Paper chromatography
  1. Separates substances from mixtures in a solution.
  2. Works as compounds are more soluble than others in the solvent. E.g. To separate food colourings.
1.5 History of the atom
1. Greeks had the first idea about the idea.
2. Early 1880's, Dalton linked his ideas to strong experimental evidence.
  1. Suggested that atoms are tiny, hard spheres. Couldn't be split or divided.
3. At the end of the 1800's, Thompson discovered electrons, and proposed the plum pudding model. This suggested that negative electrons were embedded in a ball of positive charge.
1.6 Structure of the atom
1. Made of protons, neutrons and electrons.
2. Protons have a plus one charge.
  1. Relative mass of these are one.
3. Neutrons have no charge.
4. Electrons have negative one charge.
  1. Relative mass of these are one.
5. Atomic number = number of protons/electrons
6. Mass number = protons + neutrons
1.7 Ions, atoms and isotopes
1. Atoms gain electrons from negative ions, and lose from positive ions.
2. Atomic number is the bottom one, mass number is the top.
3. Isotopes have the same atoms in them, but different amounts of neutrons.
  1. Identical chemical properties, physical, like density, can differ.
1.8 Electronic structure.
1. Electrons in an atom are arranged in shells.
2. Lowest energy levels contain up to 2 electrons, highest electrons contain up to 8 electrons.
3. After 8 electrons occupy the 3rd shell, the 4th shell starts to form.
4. The number of electrons in the outermost shell determine how it reacts.

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