Atomic structure, spectra and electron configurations Flashcards
EL1
what are atoms made from?
protons, neutrons and electrons
give the characteristics of an electron
- electrons have a -1 charge
- they wizz around the nucleus in shells, these shells take up most of the volume of the atom
give the characteristics of the nucleus
- most of the mass of the atom is concentrated in the nucleus
- the diameter of the nucleus is rather titchy when compared to the whole atom
- the nucleus is where you find the protons and neutrons
whats the relative charge and mass of a proton?
charge: +1
mass: 1
whats the relative charge and mass of a neutron?
charge: 0
mass: 1
whats the relative charge and mass of an electron?
charges: -1
mass: 1/2000 (negligible)
what do ions have different numbers of?
ions have different numbers of protons and electrons
- negative ions have more electrons than protons
- positive ions have fewer electrons than protons
what are isotopes?
isotopes are atoms of the same element with different numbers of neutrons
describe the nuclear model and how Rutherford proved this?
- a tiny, positively charged nucleus at the centre, surrounded by a cloud of negative electrons. most of the atom is empty space
- Rutherford fired alpha particles at a thin sheet of gold, the expectation was that most would be very slightly deflected but in fact almost all passed directly through and a very small number were deflected. this proved the plum pudding model incorrect and made the nuclear model.
describe the plum pudding model
a positively charged sphere with negative electrons embedded in it
describe the bohr model
- electrons exist in fixed orbits, or shells and not anywhere in between.
- each shell has a fixed energy
- when an electron moves between shells electromagnetic radiation is emitted or absorbed
- because the energy of the shells is fixed, the radiation will have a fixed frequency
what particle did J J Thompson discover?
the electron
what is relative atomic mass?
relative atomic mass is the mean weighted mass of an atom of an element compared with the 1/12th the mass of an atom of carbon-12
what is relative molecular mass?
relative molecular mass is the mean weighted mass of a molecule compared with 1/12th the mass of an atom of carbon-12
what is relative formula mass?
relative atomic mass is the sum of the mean weighted masses of all atoms in the formula of a compound compared with 1/12th the mass of an atom of carbon-12
what is a mole?
a mole is the amount of substance containing as many particles as there are atoms in 12g of carbon-12
what is an ionic equation?
an ionic equation is an equation in which only the non-spectating ions are shown
how is percentage yield calculated?
= (actual yield/expected yield) x 100
how is percentage composition by mass calculated?
= (mass of desired substance/mass of mixture) x 100
how is a standard solution prepared from a concentrated solution?
- a certain volume of the concentrated solution is added to a volumetric flask in order to get the desired final volume
- distilled water is added to the volumetric flask up to the line on its neck
how do you calculate the mass spectrometry of an element?
(%abundance x mass number) + same for all other isotopes / 100
describe empirical and molecular formulas?
empirical: the simplest ratio of all the elements present in the simplest formula
molecular: the actual number of each type of atom present in one molecule of a compound
define atom?
smallest piece of an element, contains protons and neutrons and is overall neutral
what is a group and a period on the periodic table?
Group: a vertical column in the periodic table, same number of electrons in outer shell
Period: a horizontal row of elements in the periodic table, all with the same number of electron shells
