Chemistry Unit 1 - Trends and Bonding Flashcards
Atomic Radius
GREATEST AND LEAST ATOM AFFECTED
atom’s size (nucleus to outer e-)
measured in pm (picometers)
Fr GREATEST
He LEAST
Atomic radius going _________ a group
As the atomic radius goes DOWN a group, the Atomic radius INCREASES
Due to shielding Effect : Reduces effective nuclear charge that outermost e- feels from nucleus
Atomic Radius going ________ a period
AR going R-L a period INCREASES b/c it is on the same energy levels
as number of protons in nucleus goes up, nuclear charge goes UP
Effective Nuclear Charge
attractive force experienced by e- due to positive atom nucleus
ENC increases _________ a period
increases L-R: Shielding effect remains CONSTANT since e- added to SAME shell
Stronger nuclear charge = GREATER attraction between nucleus and outer e-
ENC increases ______________ a group
Increases UP a group: LESS Shielding means less number of e- shells = stronger attraction between nucleus + outer shell
ENC and AR proportionalities
INVERSE
Shielding Effect
- and - repel, + and - attract
how inner e- REDUCE effect nuclear charge that outer e- experience, LESS tightly bond to nucleus
MORE E- SHELLS = MORE SHIELDING
DOWN a group = more shielding
Ionic Radius
POSITIVE CATION + NEGATIVE ANION
size of ionic atom (radius to outer shell)
POSITIVE CATION : SMALLER
-fewer e- in orbit, nucleus can pull more e-
AR- ENC +
NEGATIVE ANION: BIGGER
- more e- in outer orbit = more repulsion, farther from nucleus
AR + ENC-
Ionization Energy (equation)
amount of ENERGY required to REMOVE an e- in gaseous state
measured in kj/mol
x(g) + energy -> [x]+ and e-
Ionization energy increase in a group
Increases UP : AR is lower, outer e- closer to nucleus and shielding effect =fewer inner electron shels meaning takes MORE energy to REMOVE e- from stom with a stronger attraction between e- and nucleus
Ionization energy increase in a period
Increase L-R: AR- , shieliding effect is constant since e- added on same shell
more energy is NEEDED to overcome stronger attraction between nucleus and outer e-
Highest and lowest effected by ionization energy
highest : He
Lowest: Fr
Electron Affinity
energy change when an e- is ADDED to an atom (energy is then released)
[how well an atom attracts an e-]
LOWEST + HIGHEST electron affinity
LOWEST: Nobel Gases (since alr happy)
HIGHEST: Halogens (high desire to gain e-)
Electron Affinity increasage in a group
Increases UP: AR- , stronger nuclear attraction
atom more liekly to gain e- when smaller, experiences stronger pull from nucleus, ENC+
Electron Affinity increasage in a period
Increase L-R: atoms have stronger nuclear charge, AR- and ENC +
more likely to gain e- and results in more energy release when e- added
Electronegativity
Atoms ability to attract e- in a chemical bond
(0-4 scale)
Electronegativity increases in a group
UP: atoms become smaller, have stronger ENC and can attraction bonding e- more strongly
weaker shielding effect
Electronegativity increases in a period
L-R: Stronger nuclear charges, AR- and ENC+
Which all increase atom’s ability to attraction bonding e-
Electronegativity LOWEST + HIGHEST
LOWEST: Fr
HIGHEST: F
Isoelectronic
same number of electrons as Noble gas (aka full)
Properties: white, solid crystal @ room temp, no/weak odour, hard + brittle,
HIGH melting and boiling point.
dissolve readily in water
conduct electricity when dissolved (electrolyte)
Ionic Compound
Properties: Made of millions of molecules
either gas/solid/liquid at room temp
usually gas : LOW boiling and melting point
waxy, flexible, rigid
Does NOT dissolve in water
poor conductivity when dissolved
may have strong odour at room temp
Molecular compound
exceptions to Octet rule:
1) Molecular compounds with ODD number of e- like NO unable to get full octet
2) molecules where atoms under 8 have less than an octet (B/Be)
3)Molecules where atom has MORE than octet (Xe, P) will always have an extra e-
EN of 0.5>
Non-Polar Covalent
EN of 1.7>
Polar Covalent
EN of 1.7<
Ionic
