Atomic Structure Flashcards
why do isotopes of the same element have the same chemical properties
they have the same electron configuration
state the different atomic models in chronological order
john dalton- solid sphere model
j.j thomson- plum pudding model
ernest rutherford- nuclear model
niels bohr-planetary model (current)
erwin - quantum model
summarise the properties of the subatomic particles
proton neutron electron
relative mass 1 1 1/1840
relative charge +1 0 -1
what does the charge of an atom show
numbers of electrons gained/lost
why do isotopes have different physical properties
they have different numbers of neutrons so they have different masses
describe what evidence was found to support Rutherford’s model
-rutherford fired He^2+ ions (alpha particles) at a sheet of gold foil, most went through to other side but small amount bounced back
-when these ions were detected behind the gold foil he concluded that most of the atom was empty space
-when a small number of ions were detected in front of the gold foil he concluded that the atom had a small positive nucleus
what are the key differences between Thomson’s and Bohr’s model
-the bohr model has a positive nucleus
-the bohr model has protons and neutrons in the nucleus
-bohr’s model has electrons in shells/energy levels and these orbit the nucleus
where did the evidence to support the electrons being arranged in shells come from
from measuring ionisation energies
define ionisation energy
IE is the amount of energy needed to remove one mole of electrons from one mole of atoms in a gaseous state
write an equation for the first ionisation energy of potassium
K (g)→K+ (g) + e-
what 3 factors will influence ionisation energy
nuclear charge (num of protons)
distance from nucleus
shielding
what are the series of ionisation energies known as
SUCCESSIVE ionisation energies
what happens to the IE when an electron is removed from a new shell
there’s a large increase in IE as the electron being removed is closer to the nucleus
which element has the highest 1st IE
Helium because it has the least amount of shells and shielding than any other atom so it will have the strongest attraction between its outer electron and nucleus so lots of energy s needed to remove its electron.
why is Li a bigger atom than Be
-they are on the same period so they have similar shielding however
*Be has more protons than Li so it has a stronger attraction between the outer electron and nucleus therefore
-t goes closer to nucleus.
why is Li a bigger atom than He
-it has more shells than He so there’s more shielding
-so there’s a weaker attraction between outer electron and nucleus as there’s a larger atomic radius
-so He will go closer to nucleus
why is Li+ a smaller ion than F-
-F- has more shells than Li+ so it has a greater distance and more shielding
-so there’s a weaker attraction between its outer electron and nucleus
-so its bigger
where are orbitals found
within each shell there’s a sub shell and within each subshell we find orbitals
what is an orbital
its a region within an atom which can hold up to two electrons with opposite spins
how many orbitals is there in;
-the s sub-shell
-the p sub-shell
-the d sub-shell
- 1
-3
-5