Flashcards
8G - Compounds & Mixtures
Flashcards do conjunto (22)
- 1ElementsSimple substances that cannot be split up in a chemical reaction
- 2AtomsSmallest particles of an element that can exist
(Atoms in an element are all the same) - 3Chemical SymbolEach element has its own chemical symbol
Oxygen = O - 4Periodic TableSymbols for all known elements are shown in this table.
- 5MoleculesSome elements have their atoms joined together in small groups called molecules
- 6CompoundsElements that are joined together.
Contains 2 or more elements joined together by bonds.
Compounds made form 2 elements always have a name that ends in "ide" - 7Compounds (cont'd)Always contains the same elements in the same ratio.
- 8Chemical FormulaThis formula tells you the ratio of Atoms of each element that are bonded together.
H2O = 2 Hygrogen to 1 Oxygen
= Water - 9Properties of CompoundsVery different from the elements that make it up. eg Hydrogen is an explosive gas, Oxygen will relight a glowing splint. Together they create water which will put out a fire.
- 10Chemical ReactionCompounds can be made to react by mixing them with other chemicals, or by using heat or electricity.
= a change in colour or a gas is given off - 11CombustionMost chemical reactions involve an energy change which is usually in the form of heat eg burning.
- 12Chemical Reactions (Cont'd)= A new substance is formed.
Most chemical reactions are not easily reversed (irreversible) - 13Precipitate or Precipitation reactionSome chemical reaction occur just by mixing substances together.
A solid (or precipitate) forms by mixing 2 liquid in a precipitation reacion - 14Decomposed - DecompositionSome chemical reactions need energy to start them off.
eg compounds are broken up or DECOMPOSED by heat. - 15Word EquationsChemical Reaction
Chemicals you start with are called REACTANTS.
The chemicals at the end are called the PRODUCT - 16Word equation exampleMagnesium + Oxygen (the reactants) =
Magnesium Oxide (the product) - 17Physical changes eg Melting, evaporating, condensing and freezingIn a physical change no new substance is formed and the changes are usually easily reversed.
- 18Mixtures Natural mixture examples = soil, river water, sea water.A mixture is easier to separate than the elements in a a compound.
- 19A pure substance contains a single substance, element or compound. Nothing else.Elements and compounds melt and boil at a fixed temperature.
Mixtures do note have definite melting points and boiling points. - 20AlloysA mixture of metals with one or more other elements
- 21Alloys have different properties from the pure metals.Pure gold is too soft for jewellery. Mixed with other metals like copper or silver makes it stronger.
- 22Carat SystemOriginal system used to measure the purity of gold.
1 Carat = 1 part in 24
Pure Gold = 24 Carats
12 Carat gold = 50% gold.
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- FlashCards sobre 8G - Compounds & Mixtures, criado por krissy em 08-06-2013.
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- krissy
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