GCSE follow-through concepts Flashcards
Relative isotopic mass
The mass of the isotope relative to 1/12 of the mass of a carbon-12 atom
The mass of which atom are the masses of other atoms measured relative to?
Carbon-12
Relative isotomic mass (Ar)
The weighted average of the masses of the isotopes on a scale where the mass of a carbon-12 atom is exactly 12 units
Relative formula mass (Mr)
The weighted average of the masses of the formula units on a scale on which the mass of a carbon-12 atom is exactly 12 units
Molecular formula
Elements in a molecule and the number of atoms of each element
Empirical formula
Simplest whole number ratio of the atoms of each element in a compound
How do you calculate Mr?
add up each individually multiplied molecule in the compound
How do you calculate the percentage of an element in a compound?
Ar of that element
————————— x100
Total Mr
How do you calculate the mass of an element produced/required for a reaction?
Mr?
—— x mass
Mr √
How do you form empirical formulas?
% or mass
————– (then use a ratio)
Ar
What is the Avogadro constant?
The number of atoms per mole of the carbon-12 isotope
What’s a mole?
The amount of any substance containing as many particles as there are carbon atoms in 12g of the carbon-12 isotope.
What’s the mass, moles and Mr triangle?
Mass
—————
Moles | Mr
How do you work out the % of a product?
Mass produced
———————- x 100
Maximum possible
What are isotopes?
Isotopes are atoms of the same element with the same number of protons, yet a different number of neutrons, therefore the atomic number remains the same, whilst the mass number changes.
What does the nucleus of an atom contain and what are their charges?
Positively charged protons and neutral neutrons
What’s in the shell of an atom and what are their charges?
Negatively charged electrons
What are the masses of protons, neutrons and electrons?
Protons and neutrons = 1 unit
Electrons = 0 units (incredibly light)
How are atoms charged and why?
They have no charge as there’s an equal number of protons and electrons
What does the atomic/proton number show us?
The number of protons in an atom
What does the nucleon/mass number show us?
The number of protons and neutrons in an atom
How do we work out the number of neutrons in an atom?
Mass number - atomic number
In which direction are groups on the periodic table and what do they show us?
Downwards, showing us the amount of outer electrons an atom has
In which direction are periods on the periodic table and what do they show us?
Across, showing us the amount of orbits an atom has
When are ions formed?
When a non-metal and a metal come into close contact
Do metals or non-metals have a pretty full outer orbit?
Non-metals
Do ions have a charge? Why?
Yes, as they contain a different number of protons and electrons
How are covalent bonds formed and with what type of atoms?
Between non-metals, who have to lose or gain three or four electrons, therefore they bond to share pairs of electrons through a covalent bond
Which number do you look at on the periodic table for bonding questions?
The top one
What do elements with a covalent bond create?
A molecule
How are molecules charged?
They have no charge or loose electrons
What is molar mass measured in?
gmol-1
What are the different symbols commonly used for mass, moles and Mr?
Mr - M
Mass - m
Moles - n
Do you use the big numbers to calculate relative formula mass?
Never
