C1 Flashcards
What are all substances made of?
Atoms
What is an atom?
The smallest part of an element which can exist.
Roughly how many elements?
100
What is a compound?
Compounds contain two or more elements chemically combined in fixed proportions
What’s group 1 called in the periodic table?
Alkali metals
What’s group 7 called in the periodic table?
Halogens
What’s group 0 called?
Noble gases
What is a mixture?
A mixture consists of two or more elements or compounds not chemically combined together.
Where would you use filtration?
Separating a solid from a liquid.
Where would you use simple distillation?
Evaporating 2 liquids with really different boiling points.
Where would you use fractional distillation?
Evaporating and separating more than 2 liquids with similar boiling point
What is crystallisation?
Separates a soluble solid from a liquid.
What is chromatography?
A method to separate different dyes in an ink.
What does soluble mean?
Able to be dissolved, especially in water
Method of paper chromatography - practical
- Draw a line near the bottom of the paper in pencil (as they’re insoluble) - Add a spot of ink and put paper in solvent (water) (ink shouldn’t touch solvent) - Place a lid to stop solvent from evaporation - The solvent seeps up, carrying the ink and each will love at a different rate - Take the paper out and leave to dry
Why might a scientific model be changed?
New experimental evidence
Before the discovery of the electron what were atoms thought to be?
Atoms were thought to be tiny spheres that could not be divided.
What discovery of led to the plum pudding model?
Electron
What does the plum pudding look like?
Sea of positive charge with negative electrons inside.
What did the results from the alpha particle scattering experiment lead to?
The mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged.
What replaced the plum pudding model?
Nuclear model
Who adapted the nuclear model?
Niels Bohr
What did Bohr discover?
Electrons orbit the nucleus at specific distances.
What is the name of the divided up positive charge?
Protons
What was the work done by James Chadwick?
He discovered neutrons
What are the charges of protons, neutrons, and electrons?
Proton +1 Neutron 0 Electron -1
Why do atoms have no overall charge?
Because they have the same numbers of protons and electrons
What is the radius of an atom?
0.1 nm (1 x 10 to the power of -10 m)
What’s the radius of the nucleus?
1 x 10-14 m
What are the masses of protons, neutrons and electrons?
Proton 1 Neutron 1 Electron - very small
What is the sum of proton and neutrons?
Mass number
What are isotopes?
Atoms of the same element with different numbers of neutrons
What is the relative atomic mass?
The average mass of all the isotopes
What is the pattern for electrons on the shells?
288
Where is the lowest energy level?
Closest to the nucleus
What did Mendeleev do?
Left gaps in his table for unknown elements and made predictions about their properties
What form positive ions?
Metals
What form negative ions?
Non - metals
Why do noble gases not react?
Stable arrangement of electrons - full outer shell
Does the boiling point increase or decrease when you go down group 0?
Increases
Does the reactivity increase or decrease when you go down group 1?
Increase
lithium + oxygen =
Lithium oxide Tarnishes slowly
sodium + oxygen =
Sodium oxide Tarnishes a bit quicker
potassium + oxygen =
Potassium oxide Tarnishes very quickly
lithium+ water =
Lithium hydroxide Floats, fizzes, disappears Hydrogen released
sodium + water =
Sodium hydroxide Melts to form a ball, fizzes rapidly, disappears Hydrogen released
potassium + water =
Potassium hydroxide Floats and melts, moves quickly around, self-ignites, lilac flame, small explosionHydrogen released
lithium + chlorine =
Lithium chloride Crimson flame
sodium + chlorine =
Sodium chloride Yellow flame
potassium + chlorine =
Potassium chloride Lilac flame
What type of element is group 7?
Non - metals
What does fluorine look like?
Poisonous yellow gas
What does chlorine look like?
Poisonous, dense green gas
What does bromine look like?
Dense, red - brown volatile liquid
What does iodine look like?
Dark grey solid or purple vapour
When you go down group 7, is it more reactive?
No, as you go down it’s less reactive
When you go down group 7, is there a higher boiling point?
Yes
Why is iodine less reactive?
There are more electrons so more shells so weaker attraction from positive nucleus to negative electron
How does displacement in group 7 work and what does it produce?
The more reactive halogen displaces the less reactive halogen which creates a salt (ide)
