iGCSE Chemistry: Calculations
Terms in this set (18)
State the mass and charge of a neutron
Neutron: mass=1, charge =0
State the mass and charge of a proton
Proton: mass=1, charge=+1
State the mass and charge of an electron
Electron: mass=negligible, charge=-1
State the particle that is found in the shells orbiting the nucleus
State the particles that are found within the nucleus of an atom
Protons and neutrons
What are the three subatomic particles?
protons, neutrons and electrons
What are isotopes?
Isotopes are atoms of the same element (same number of protons) but with a different number of neutrons (different mass)
What is a mass number?
Mass number is the number of protons plus the number of neutrons in an atom
What is an atomic number?
The atomic number is the number of protons in an atom
What is meant by the term relative atomic mass, Aᵣ?
The average mass of an atom of an element, relative to 1/12th of the mass of an atom of carbon-12
A sample of bromine contained the two isotopes in the following proportions: bromine-79 = 50.7% and bromine-81 = 49.3%. Calculate the relative atomic mass of bromine
((79x50.7)+(81x49.3))/100 = 79.99
How many electrons can the first, second and third shells hold?
First 2, second 8, third 8
Calculate the relative formula mass(Mr) of carbon dioxide (CO₂)
State the steps for calculating empirical formula
1) mass/Ar. 2) divide by the smallest. 3) Give the ratio has a whole number. 4) State final empirial formula
What is meant by the term empirical formula?
A chemical formula that shows the simplest ratio of the numbers of atoms in a compound
What is meant by the term molecular formula?
A chemical formula that shows the actual numbers of the different types of atoms in a molecule
An oxide of nitrogen contains 26% nitrogen and 74% oxygen and has a relative molecular mass of 108. Find the empirical and molecular formulae for the oxide.
Empirical formula is N₂O₅. Molecular formula is also N₂O₅
To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is the crucible is cooled, weighed, reheated, cooled, re-weighed, and so on?
To make sure a constant mass has been reached and there is no more magnesium left to react
OTHER SETS BY THIS CREATOR
iGCSE Chemistry: Ionic Bonding
iGCSE Chemistry: Specification Experiments
iGCSE Chemistry: Key Calculations (Triple)
iGCSE Chemistry: Equilibria (Triple)
THIS SET IS OFTEN IN FOLDERS WITH...
iGCSE Chemistry: Fundamentals
iGCSE Chemistry: Separating Techniques
iGCSE Chemistry: Key Reactions
iGCSE Chemistry: Simple Molecules & Covalent Bonding