# CHEMISTRY- elements, equations, key definitions

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History of Pt- Johann Dobereiner
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John Newlands
law of octaves - found that every eighth element was similar, however after a while this didn't work
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Dmitri Mendeleev
arranged his elements into columns and left gaps for undiscovered elements
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pt- group 1/ alkali metal properties
get less stable as you go down the group, reactivity increases down the group, 1 electron in outer shell, highly reactive- stored in oil, (e-) ions form (+1) ions in reactions
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pt- group 7/ halogens properties
react with hydrogen to form halides, all have 7 electrons in outer shell, reactivity decreases down the group, a more reactive halogen will push a less reactive halogen out of that compound
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pt- transition metal properties
less reactive, all have useful properties, hard, malleable, ductile, strong, conducts electricity
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pt - how to work out atomic number, mass number, neutrons
atomic number- (bottom number) is the number of protons, mass number (top) number of protons+neutrons, no of neutrons= mass number- atomic number
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what is an ion?
An ion is a charged atom. Positive if they lose and electron and negative if they gain an electron. positively charged atoms= CATION. negatively charged atoms= ANION
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Ionic bonds + covalent bonds
Ionic bonds occur between metals AND non metals where electrons are transferred. Covalent bonds occur between two NON metals only, where electrons are shared e.g water
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Quantitative chem- moles definition + formula
A mole is the relative formula mass of a substance in grams. 1 mole of an element contains 6.02 x 10(23) of that element (avogadros constant) e.g 1 mole of potassium contains 6.02 x 10(23) atoms of potassium
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number of moles formula (e.g how to calculate the mass of 4 moles of lithium)
No of moles= mass (g)/ molar mass N=M/m. example: mass of lithium= 7(g) 7x4(moles)= 28g
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limiting reactants
the amount of product produced in a reaction depends on the amount of reactant available
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Volume and concentration formulas
volume= dm(3) 1cm(3)= 0.001dm(3) Concentration= mass of a substance(g)/ volume of solvent(dm(3)). To convert g/dm(3) into mol/dm(3)= concentration(g/dm(3))/ molar mass
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Percentage yield
percentage yield= actual yield made/ theoretical yield (what was supposed to be made) x100 (to make percentage)
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Atom economy- definition+ formula
Atom economy is how productive an atom is. Atom economy= mass of useful products/ mass of all products x100 (to make percentage) - if an atom has a low atom economy then it is inefficient
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Titrations (neutralisation)
A titration experiment is using a known concentration of one solution to calculate the unknown concentration of another =
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Electrolysis
electrolysis is splitting substances using electricity. PANIC= Positive Anode Negative Is Cathode. electrolysis of an aqueous solution is factoring the ions in the water as well (H+) (OH-)
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endothermic and exothermic reactions + examples
endothermic= a reaction that takes energy in from the surroundings- e.g photosynthesis. Exothermic= gives off energy to the surroundings(heat, light energy) e.g fire
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Reactions of metals with: 1) oxygen 2) water 3) acid. what is formed
1) metal+oxygen=metal oxide. 2) metal+water= metal hydroxide. 3) metal+acid=salt+hydrogen (MASH)
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name 5 separation techniques
1, filtration 2, chromotography 3, evaporation 4, crystallisation 5, distillation
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## Other cards in this set

### Card 2

#### Front

law of octaves - found that every eighth element was similar, however after a while this didn't work

John Newlands

### Card 3

#### Front

arranged his elements into columns and left gaps for undiscovered elements

### Card 4

#### Front

get less stable as you go down the group, reactivity increases down the group, 1 electron in outer shell, highly reactive- stored in oil, (e-) ions form (+1) ions in reactions

### Card 5

#### Front

react with hydrogen to form halides, all have 7 electrons in outer shell, reactivity decreases down the group, a more reactive halogen will push a less reactive halogen out of that compound