Atomic Radius (2)
- the distance from the centre of an atom to the boundary within which the electrons spend 90 % of their time.
- In a diatomic molecule → the distance between the two nuclei, divided by 2
Atomic Radius Moving Down (4)
Increases moving down
- each additional energy level is a greater distance from the nucleus
- The electrons situated on the inner levels “shield” the outer electrons from the full charge of the nucleus
- As a result, the outer electrons are not as strongly attracted to the nucleus → larger atomic radius
Atomic Radius Moving Left to Right (4)
Decreases
- This is a direct result of the increasing positive charge of the nucleus
- As you move across a period, each element has one more proton and one more electron than the element before it → the attraction of the electrons towards the nucleus increases (the e- are drawn closer to the nucleus resulting in a smaller atomic radius
Ionization Energy (3)
- The amount of energy required to REMOVE a single valence electron from an atom or ion in the gaseous state
- Removing electrons requires energy
Gaining electrons usually releases energy
Ionization Energy Moving Down (4)
Decreases
- the force of attraction between the electron and nucleus decreases as atomic radius increases
- The farther away an electron is from the nucleus, the easier it is to remove!
- Going down, the element is more reactive
Ionization Energy Moving Left to Right (2)
increase.
- As atomic radius decreases, the pull on the outermost electrons increases making it harder to remove them
Electron Affinity (1)
The energy change (ABSORBED or RELEASED) that occurs when an electron is added to a neutral atom in a gaseous state (aka gained an electron)
Electron Affinity Moving Down (3)
decreases
- The attraction to the nucleus decreases
Fr has the least negative value
→ large radius, nucleus has a weak hold on the 1 valence electron
→ not very much energy will be given off to accept an electron
Electron Affinity Moving Left to Right (4)
- Increases
the number of valence electrons increases and the atomic radius decreases
The attractive force between the nucleus and the valence electrons increases, so more energy is released when a new electron is acquired
Noble gases do not form stable ion, if 1 electron is added → unstable, incomplete outer shell (no energy given off so unstable)
Halogens - forms a very stable ion when 1 electron is added → complete outer shell (a lot of energy given off)
Electronegativity (1)
An indicator of the relative ability of an atom to attract shared electrons
Electronegativity Moving down(1)
Electronegativity Decreases
Atomic radius increases moving down the PT, the attraction between the valence electrons and the nucleus decreases due to distance and electron cloud. Therefore weaker hold on electrons
Nucleus of larger atoms cannot get close enough to attract another atoms electrons
Electronegativity Moving left to right(1)
Moving across a period
Electronegativity Increases (left to right)
The atomic radius decreases moving across the period
The attraction between the nucleus and the valence electrons increases due to distance. Therefore a stronger hold on electrons
Nucleus of a small atom can get close enough to attract another atoms electrons
Ionic Radius (4)
Cations and Anions have different sizes
When an atom loses an electron, it forms a positive ion (cation)
Since it is losing electrons, there is less repulsion between electrons and more attraction to the nucleus so the ionic radius is smaller than the atomic radius
When an atom gains an electron, it forms a negative ion (anion)
Since it is gaining electrons, there is more repulsion between electrons and less attraction to the nucleus so the ionic radius is larger than the atomic radius
Ionic Radius Moving Down
Increases down a group
- farther from the nucleus
Ionic Radius Moving Left to Right
Decreases
Cations (positively-charged ions)
Cations are smaller than their parent atom because the same number of protons in the nucleus pulls on less electrons.
Metals commonly become cations.
Anions (negative ions)
Anions are larger than their parent atom because the same number of protons in the nucleus pulls on more electrons.
Nonmetals commonly become anions.
