C1 - Atomic Structure
- Created by: izz08
- Created on: 27-11-17 19:24
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- Atoms
- All substances are made of atoms
- The periodic table lists all the chemical elements, with eight main groups each containing elements with similar chemical properties
- Compounds contain more than one element
- Elements are made of only one type of atom
- C1 - Atomic Structure
- Chemical equations
- No new atoms are ever created or destroyed in a chemical reaction: the total mass of reactants = the total mass of products
- There is the same number of each type of atom on each side of a balanced symbol equation
- You can include state symbols to give extra information in balanced symbol equations.
- Separating mixtures
- A mixture is made up of two or more substances that are not chemically combined together
- Mixtures can be separated by physical means, such as filtration, crystallization and simple distillation
- Fractional distillation and paper chromatography
- Fractional distillation is an effective way of separating miscible liquids, using a fraction column. The separation is possible because of the different boiling points of the liquids in the mixture
- Paper chromatography separates mixture of substances dissolved in a solvent as they move up the piece of chromatography paper. The different substances are separated because of their different soulubilities in the solvent used
- History of the atom
- New evidence has been gathered by scientists who have used their model of the atom to explain their calculations and observations
- Key ideas were proposed by Dalton, Thomson, Rutherford and Bohr.
- Structure of the atom
- Atoms are made of protons,neutrons and electrons
- Protons have a relative charge of 1+, and electrons have a relative charge of -1. Neutrons have no charge, they are neutral.
- The relative masses of protons and neutrons are both 1
- Atoms contain an equal number of protons and electrons so carry no overall charge
- Atomic number = number of protons
- Mass number = number of protons + neutrons
- Ions, atoms and isotopes
- Atoms that gain electrons form negative ions. If atoms lose electrons they form positive ions
- Isotopes are atoms of the same element with different numbers of neutrons. They have identical chemical properties, but their physical properties, such as density can differ.
- Electronic structures
- The electrons in an atom are arranged in energy levels or shells
- The lowest energy level (1st shell) can hold up to two electrons and the next energy level (2nd shell) can hold up to eight electtrons
- The number of electrons in the outermost shell of an elements atoms determines the way in which that element reacts
- Chemical equations
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