PAPER 1 GCSE Flashcards
What is an ELEMENT?
A substance containing only one type of atom
eg. Mg, O2
What is a COMPOUND?
A substance containing two or more different types of atoms which are CHEMICALLY BONDED
eg. H20
Why must equations be balanced?
Atoms cannot be created or destroyed due to CONSERVATION OF MASS
What is a PRO TIP when balancing equations?
Start with atoms in a compound; end with elements.
What is a MIXTURE?
A mixture consists of different substances NOT CHEMICALLY BONDED
eg. air, solutions.
What does FILTRATION do?
Removes large, insoluble particles from a liquid
eg. sand from water
What does CRYSTALLISATION do?
Leaves behind crystals of a dissolved substance (solute)
What does SIMPLE DISTILLATION do?
Involves condensing the evaporated solvent and collecting it
What does FRACTIONAL DISTILLATION do?
Can separate liquids due to their different boiling points
What does CHROMATOGRAPHY do?
Separates mixtures of soluble substances in a solution
What are the 3 main states of matter?
Solid
Liquid
Gas
What is MELTING?
Solid -> Liquid
What is SOLIDIFICATION/ FREEZING?
Liquid -> Solid
What is EVAPORATION/ BOILING?
Liquid -> Gas
What is CONDENSATION?
Gas -> Liquid
What is SUBLIMATION?
Solid -> Gas
Particles in a SOLID:
- Regular arrangement (lattice) and vibrate about fixed positions.
- Cannot be compressed
Particles in a LIQUID:
- Irregular arrangement and are able to move past each other
- Cannot be compressed
Particles in a GAS:
- Far apart, move randomly at fast speeds (high energy)
- Can be compressed
Are new substances made after a physical change?
No
What is needed to overcome the electrostatic forces of attraction between particles to melt/ evaporate?
Energy (heat)
What are the state symbols?
(s) = SOLID
(l) = LIQUID
(g) = GAS
(aq) = AQUEOUS (dissolved or in a solution)
Atomic Structure HISTORY (briefly):
ANCIENT GREEKS: thought matter to be made of invisible particles
JJ THOMPSON: Created the ‘plum pudding’ model
ERNEST RUTHERFORD: Discovered that the nucleus was small and positively charged by finding that most alpha particles went straight through a gold ‘leaf’; very few deflected back.. Atoms mostly empty space
NEILS BOHR: Deduced that electrons exist in ‘shells’. JAMES CHADWICK determined that the nucleus must contain NEUTRONS as well as protons.
What are the RELATIVE CHARGES of the three subatomic particles?
Proton = +1
Neutron = 0
Electron = -1
What are the RELATIVE MASSES of the three subatomic particles?
Proton = 1
Neutron = 1
Electron = 0.0005
What is the ATOMIC NUMBER?
The number of protons/ electrons in a nucleus
What is an ISOTOPE?
Atoms with the same number of protons but a different number of neutrons.
What happens if an atom has a different number of protons and electrons?
It is an ION.
What is the MASS NUMBER also known as?
RELATIVE ATOMIC MASS/RAM/Ar
What is the MASS NUMBER?
The number of PROTONS and NEUTRONS in a nucleus.
Why might some MASS NUMBERS on your periodic table be decimals?
They are the AVERAGE mass of all isotopes
How do you work out the AVERAGE MASS?
Average mass = total mass of 100 atoms/ 100
The RELATIVE ABUNDANCE of
Chlorine-35 is 75%
Chlorine-37 is 25%
How would this look in the formula for average mass?
(35x75)+(37x25)/ 100 = 35.5
How were the elements initially ordered in the periodic table?
According to their atomic ‘weight’
How did Dmitri Mendeleev organise the periodic table?
He grouped elements together based on their properties.
Why did Dmitri Mendeleev believe there were gaps in his table?
Elements had yet to be discovered.
In time, this was proven to be largely correct, and is the basis of the modern periodic table.
Electron configuration?
2,8,8,2
Which ions do metals form?
Positive
Which ions do non-metals form?
Negative
What is Group 1 called?
The Alkali Metals
What is Group 7 called?
The Halogens
What is Group 0/8 called?
The Noble Gases
How does the reactivity of Group 1 change throughout the group?
Why?
Group 1 gets more reactive as you go down the group.
This is because the outer electron is further from the nucleus so the attraction between the outer electrons and the nucleus decreases.
How does the reactivity of Group 7 change throughout the group?
Why?
They get less reactive as you go down the group.
This is because the number of electron shells increases, so the attraction between the nucleus and outer electrons decrease which makes it harder to gain an electron.
How does the reactivity of Group 0/8 change throughout the group?
Why?
The are unreactive as they already have an empty outer shell.
