Atomic structure, periodic table and calculation paper 2 Flashcards
What is an atom
an atom is the smallest part of an element
What is a molecule
A molecule is made of a fixed number of atoms covalently bonded together.
Proton neutron and electron mass
Proton - 1
Neutron - 1
Electron - almost negligible
Proton neutron electron charge
Proton - 1
Neutron - 0
Electron - -1
What is atomic mass
The number of protons in an atom.
What is mass number
The number of protons and neutrons in an atom.
What is relative atomic mass
The average mass of an atom compared to 1/12th the mass of carbon-12
What are isotopes
Atoms of the same element (same number of protons) but with a different number of neutrons.
Groups are
Columns, they show the number of atoms in the outer shell
Periods are
Rows, they show the number of shells in an atom
Metals have oxides which are
basic, reacting with acids to give a salt and water
Non metals have oxides which are
acidic or neutral
why the noble gases (Group 0) do not readily react
The noble gases are inert (unreactive) because they have a full outer shell of electrons.
What is mole
unit for the amount of a substance
The mass of 1 mole of a substance is the relative formula mass (Mr) of the substance in grams
mol =
mass / Mr
grams over rams
What is the theoretical percentage yield
The theoretical yield is the amount of product that you would expect to get.
percentage yield =
actual amount of a product / theoretical percentage yield
Finding the formula of a metal oxide experimentally
Finding the formula of a metal oxide experimentally
- Weigh a crucible and lid
• Place the magnesium ribbon in the crucible, replace the lid, and reweigh
• Calculate the mass of magnesium
• Heat the crucible with lid on until the magnesium burns
• Lift the lid from time to time (this allows air to enter)
• Stop heating when there is no sign of further reaction
• reweigh
• Repeat the heating , cooling and reweigh until two consecutive masses are the same
• Calculate the mass of magnesium oxide formed
Finding the formula of a salt containing water of crystallisation
When some substances crystallise from solution, water becomes chemically bound up with the salt. This is called water of crystallisation and the salt is said to be hydrated.
The difference of mass before and after heating is the mass of the water lost
What is the empirical formula
the simplest whole-number ratio between atoms/ions in a compound
What is a molecular formula
the actual number of atoms of each type of element in a molecule.
concentration ( mol/dm3) =
mol =
mol / volume
concentration x volume
volume of a gas =
mol x 24 dm3
To determine the formula of a metal oxide by combustion
Weigh a crucible and lid
Place the magnesium ribbon in the crucible and reweigh
Calculate the mass of magnesium
Heat the crucible with lid on until the magnesium burns
Lift the lid from time to time
Stop heating when there is no sign of further reaction
Allow to cool and reweigh
Repeat until two consecutive masses are the same
Calculate the mass of magnesium oxide formed- empirical formula
