Y9 Chemistry Flashcards
What is a mole?
A standard scientific unit for measuring large quantities of very small entities such as atoms or molecules.
Solid particle structure
Solid particles are very tightly packed together. They are low in energy compared to the particles in a liquid or a gas. As they are si tightly packed together they can only vibrate. The shape of a solid is fixed and cannot change.
Liquid particle structure
Liquid particles are more spread out and can move about more than solid particles. They have more energy compared to solid particles. Most of the the particles are touching. Liquids can change their shape to fill a container.
Gas particle structure
Gas particles are much more spread out. They are free to move about more and do not permanently touch each other. They have more energy than liquids and solids.
The nucleus of an atom
Protons and neutrons exist in a dense core at the centre if the atom this is the nucleus.
Shells of an atom
Electrons are spread out around the edge of an atom. They orbit the nucleus in layers called SHELLS.
Proton mass and charge
Mass= 1 Charge= +1
Neutron mass and charge
Mass= 1 Charge= 0
Electron mass and charge
Mass= almost 0 Charge= -1
Avagadros constant
6.022 x 10 to the power of 23 (couldn’t write it, it would normally be a small 23 next to the ten in the top tight corner)
Relative formula mass symbol
Mr
Calculating number of moles
Number of moles (n)= mass (m) divided by Mr (relative formula mass)
Mass number
The mass number is the little number at the top of the symbol for an element. For example carbon= 12. This shows how many protons and neutrons there are.
Atomic number
The atomic number is the small number at the bottom of the elements symbol for example carbon= 6. This means that the number of protons= 6.
