Chemistry Unit One GRADE 11

atoms of the same element that have the same number of protons but different number of neutrons. Therefor their atomic mass is different

The isotope with the greatest abundance will have the greatest impact on the average atomic mass

Atoms whose center’s (nuclei) aren’t stable. To fix themselves they break down into other atoms and give off radiation in the process

electrons between the nucleus and the valence shell, these electrons block the attractive force between valence electrons and nucleus

the attraction between the valence electrons and the nucleus after considering the shielding electrons.

The distance from the nucleus to the outermost electrons

As we go down a group the atomic radius increases there are more shells as we go down, therefor more shielding electrons, so the valence electrons feel less attraction to the nucleus.

as we go across a period the atomic radius decreases, there are more protons, therefor the valence electrons feels more attraction to the nucleus.

The ionic radius is the distance from the nucleus of an ion to the outermost electron (just like AR but for ions)

when cations lose electrons the radius gets smaller

when an atom gains electrons (forms anion) extra electrons repel each other and spread out. Radius gets larger

Reactivity increases, shielding electrons increase so the attraction between the nucleus and valence electrons decrease, therefor easier to remove electrons

Reactivity decreases, as we go left to right atomic radius decreases so the attraction between the valence electrons and the nucleus increase therefore it’s harder to remove an electron

Reactivity increases, the shielding electrons decrease so there is a stronger attraction between the valence electrons and nucleus therefore gained electrons will be held closer.

Reactivity increases, atoms are closer to becoming stable with a full octet -atomic radius decreases since the shielding electrons remain the same in the number of protons increase the gained electron is held closer to the nucleus due to the strong attraction

The amount of energy required to remove a valance electron from an atom

Noble gases have very high ionization energy noble gases have a small atomic radius and full shells therefore a lot of energy is needed to remove an electron

Going down the group the ionization energy decreases because the atomic radius increases so there are more shielding electrons therefore less energy required to remove an electron

Going across the period the ionization energy increases because the atomic radius decreases so more protons for the same amount of shield electrons therefore valence electrons feel a strong attraction to the nucleus and more energy is required to remove an electron

The amount of energy absorbed or released when an electron is added to an atom

absorb

release

Going left to right electron affinity increases because the atom gets closer to a full shell the atomic radius decreases and protons increased so the attraction between the nucleus and the valence electrons increases.

Electron affinity decreases the atomic radius increases since the amount of shielding electrons increases therefore less attraction between valence electrons a nucleus