Topic 2 - atoms ions and compounds Flashcards
(18 cards)
Atoms are composed of what 3 things?
- Protons
- Neutrons
- Electrons
Relative mass of proton neutron and electron
- p = 1
- n = 1
- e = 0.0005
relative charge of proton, neutron and electron
- p = +1
- n = 0
- e = -1
mass number
total number of protons and neutrons in an atom
Atomic number
number of protons in the nucleus
anions
negative charged ions
cations
positive charged ions
Thomson’s Plum Pudding Model (1897)
- discovered that atoms were divisible after the discovery of electrons
- atoms as spheres with positive charge with negative electrons embedded randomly throughout
Rutherford’s gold foil experiment
- fired alpha particles (+ charged) at a sheet of thin gold foil inside a vaccum
- according to the plum pudding model, the positive sphere should slightly defelect most of the particles
Bohrs model
- electrons orbit the nucleus in
specific energy levels, or shells - Why atoms don’t collapse in on
themselves
Elements
Substance made up of only one type of atom, where all the atoms of a substance have the same number of protons
Isotopes
Atoms of the same element that have the same number of protons but different numbers of neutrons
chemical properties of isotopes
- have same electron configuration
- this means that they have the
same chemical properties e.g.
reactivity.
Physical properties of isotopes
- Different physical properties e.g.
mass and density - Because it depends on atomic
mass
Relative isotopic mass
The mass of an atom of an isotope compared to 1/12 the mass of a carbon-12 atom
Relative atomic mass
The weight mean mass of an atom of an element compared to 1/12 the mass of a carbon-12 atom
Relative molecular mass
The average mass of a molecule compareed to 1/12 the mass of a carbon-12 atom
Relative formula mass
Used for ionic compounds. Calculated by adding up the relative atomic mass values of all the ions in one formula uni.
