Chemistry - Periodic Table Flashcards
(51 cards)
What are all substances made of
Atoms
What is an atom
The smallest part of an element that can exist
What elements are the following symbols: O, NA, C
Oxygen, Sodium and Carbon
How many elements are there
118
What does the periodic table show
The elements arranged in order of atomic number
How are compounds formed
Elements combining together in chemical reactions
What always happens in a chemical reaction
One or more new substances are formed
How can chemical reactions be represented
With word or symbol equations
What is a mixture
Two or more elements not chemically joined together
Are the chemical properties changed in individual substances in mixture
No
5 physical processes that can separate a mixture
Filtration, crystallisation , simple distillation, fractional distillation, chromatography
Filtration
When a liquid is separated from an insoluble solid through filter paper. Eg separating sand from water
Crystallisation
A crystal is obtained from a solution by evaporating off the liquid. Eg making copper sulphate crystals
Simple distillation
A liquid is obtained from a solution by evaporating it off and then condensing it. Eg pure water
Fractional distillation
A mixture of liquids is heated, evaporated and then condenses at different temperatures.
Chromatography
Substances in a mixture travel up chromatography paper with solvent at different rates. Eg separating pigments in ink
What were atoms thought to be before the discovery of electrons
Tiny spheres that could not be divided
Which model of the atom did the discovery of the electron lead to
The plum pudding model
Describe the scattering experiment and what it concluded
Positively charged alpha particles were fired at thin gold foil most of them passing through some scattering in different directions. This concluded the mass of an atom is concentrated in the centre , which is the nucleus
How did Niels Bohr adapt the nuclear model
He suggested that electrons
Orbit the nucleus at specific distances
What evidence did Chadwick provide about the nucleus of atoms
The nucleus contains neutrons
Differences between the plum pudding model and the nuclear model
Plum pudding = mass distributed equally, electrons embedded in atom, positive charge evenly distributed
Nuclear model =
Mass concentrated in the centre, electrons orbit nucleus, positively charged nucleus
Relative electrical charge of a proton, neutron and electron
+1,0, -1
Why do atoms have no overall charge
The number of protons and electrons are equal
