atomic theory hard cards

Periodic table trend principles (3)

1. e- in large orbits = farther from the nucleus, less attraction to p+ bc more shielding

2. More p+ = more attraction for e- from nucleus→ effective nuclear charge (Zₑff)

3. e- in the same subshell repel each other

Atomic Radius (3)

Measure of the radius from the nucleus to the Ve- in an atom

• Down group → AR increases: More shells (higher n value) + shielding

• Across period → AR decreases: Zeff & Protons increases (Added e- joins same orbital)

Ionic Radius (4)

AR of an ion

• Cations = smaller than neutral

  • Loses electrons so AR decreases

• Anions = larger than neutral

  • Gains elections so AR increases

Ionization Energy (IE) (6)

Amount of energy needed to remove an e-

• Trend = opposite to AR, small AR → high IE

  • Elements on left need to get rid of e- to become stable

  • Elements on right need to gain e- to become stable

• Exceptions: O = lower IE₁ than N bc O wants to lose 1e- to become half filled

Electronegativity (EN) (5)

The ability to attract e-

• Measurement of an atom’s Zeff on OTHER atoms

• Atoms w/ high EN pull bonded e- closer to their nuclei

• Noble gasses have no EN value (shells stable)

• EN has the same trend as IE

Intramolecular interactions (2)

• Occur WITHIN molecules/compounds/crystals

• Includes: ionic, covalent, metallic bonds

Ionic Bonds (5)

• Forms when large difference between EN and IE of both atoms (EN >1.8)

• Metal w/ low IE/EN transfers Ve- → Non-metal w/ high IE/EN

• Electrostatic attraction-both atoms become ions after transfer

• Sometimes forms into a crystal lattice (Ex. NaCl)

  • Makes compound have a high melting point (Caused by a vast number of attractive forces in structure)

Polar Covalent Bonds (3)

• Forms when EN = 0.5-1.8

  • When e- are pulled more towards one atom bc of higher EN, one side of the moc becomes more negative than the other side (unequal sharing of e-)

    • Causes dipole (One side more negative)

Non-polar Covalent Bonds (7)

• Forms when EN < 0.4

  • Between identical/same charged non-metals

    • EN value = same; ΔEN = 0

  • Collision of atoms = electron clouds overlap

    • Attractive forces (nucleus) may begint o overlap repulsive forces (e-)

      • Pair of Ve- shared between both

      • The electrons will not be more attracted to one nuclei over the other (equidistant)

Metallic Bonds (3)

• Protons swarmed by electrons

  • “sea” of electrons makes metal malleable + conductive

  • Forms metallic crystals

Octet Rule (5)

• All atoms form stable octet when bonding

  • Stable + low-energy configuration

• EXCEPTIONS (sometimes):

  • H makes 1 bond

  • B takes less e-

  • S & P take more e-

Intermolecular Forces (4)

• Occurs BETWEEN covalent molecules

• Strength/weakness affects state of matter + chemical properties

  • Strong IMF = High BP (solid/liquid)

  • Weak IMF = Low BP (liquid/gas)

London Dispersion Forces (10)

• Weakest force but Always present

• Between 2 non-polar molecules

• Creates temporary dipole

  • When e- in moc 1 shift to one side → temporary dipole forms

    • Can induce a dipole in a nearby molecule

  • They form a temporary dip-dip before floating away

• Attraction increases w/ atomic number

  • Dipole increases when more e- is added

• Attraction increases w/ larger molecules

  • More spaces to attract

• If only LDF present → low BP + MP

Dipole-dipole (4)

• 2nd strongest force

• Between 2 polar molecules

• δ+ from moc1 attracted to δ- from moc2

• Stronger bonding = Higher BP + MP

Hydrogen Bonding (3)

• Strongest IMF

• Type of dipole-dipole (only for H)

• H bonded with atoms with high EN (N, O, F)