✨Module 2: Atoms, ions and compounds Flashcards
Nucleons are held together by …
Protons + electrons are held together by ..
Strong residual forces
Strong electrostatic forces
Mass number =
Atomic number =
Ar
Z
Chemical properties depend on …
Number and arrangement of electrons. Isotopes have same chemical properties as same no. electrons. No. neutrons have no effect on reaction.
Physical properties depend on …
Mass of atom, so isotopes have slightly different physical properties e.g. bmp.
To calculate no. electrons in a shell …
2n squared. n is the shell number.
Hydrogen atom -
Deuterium atom (D2O) -
Tritium atom (T2O) -
1 proton, 0 neutron, 1 electron.
1 proton, 1 neutron, 1 electron.
1 proton, 2 neutrons, 1electron.
Normal water is the …
Heavy water is …
Hydrogen isotope.
Deuterium. Used to control nuclear processes.
Why does deuterium have higher bmp and density than hydrogen?
Deuterium has greater mass so more surface area for contact so stronger intermolecular forces between D2O molecules. If all water were heavy water, we would see ice more often.
Oxygen-16 means …
Mass number is 16.
Define cation.
Define anion.
+ charged with fewer electrons.
- charged with more electrons than protons.
What is the carbon-12 isotope?
International standard for the measurement of atomic masses.
Relative mass compares …
Th mass of 1 atom to carbon-12
Standard atomic mass is …
Mass of carbon-12 is …
1u
12u
Define relative isotopic mass.
Mass of an isotope relative to 1/12 the mass of an atom of carbon-12. RIM = mass no!
RIM has …
It is usually …
No units and it’s a ratio of 2 masses.
A whole number.
Work out masses to …
1dp
Define relative atomic mass (Ar).
Weighted mean mass of an atom of an element relative to 1/12 the mass of carbon-12.
Is RAM a whole number?
No, as it’s an average.
RAM depends on …
% abundance of each isotope, RIM of each isotope.
Relative molecular mass (Mr) is used for …
Simple molecules (H2O, CO2). Just add up RFM of each.
Relative formula mass is the …
Same as RMM but for giant structures (ionic).
What is the mass defect?
Small amount of mass loss due to strong nuclear force holding protons + neutrons.
What does a mass spectrometer do?
Produce mass spectra, which identify RIM and abundances of each element, thus RAM.
What did JJ Thompson discover?
Plum pudding model - positively charged sphere with negative electrons in it.
What did Rutherford do in the gold foil experiment?
He fired + charged alpha particles to a thin sheet of gold foil. Most particles passed straight through and some deflected back.
What did Rutherford state?
- Tiny, positively charged central nucleus, surrounded by electrons.
- Most of the atom is empty space.
What did Bohr realise?
Electrons would be attracted to the nucleus, so he proposed that electrons are in shells and each shell has a fixed energy.
What else did Bohr state?
Atoms can react to gain an outer shell.
When electrons move between shells …
EM radiation is emitted or absorbed.
