Periodic trends

• Atomic radius is the distance from the center of the nucleus to the outermost electrons
• Atomic radius decreases across the period and increases across the group
• Effective nuclear charge (Zeff) is the amount of charge felt by the most recently added electron
• Effective nuclear charge increases down the period and slightly increases down the group
• Zeff = protons - core electrons
• Increased Zeff means electrons are pulled to the nucleus
• Decreased Zeff means electrons are pushed away from the nucleus due to increased repulsive forces
• If different ions all have the same number of electrons, the largest would be the one with the smallest number of protons because it experiences the least Zeff or nuclear attraction
• Ionization energy increases down the period and decreases down the group
• Second ionization energy is always more than the first ionization energy because Zeff increases for remaining electrons
• Electronegativity is the tendency of atom to attract electrons shared in covalent bond
• Electronegativity mnemonic: FONClBrISCH
• When bonding Hydrogen, those elements to the right of C will carry partially negative charge
• When bonding hydrogen, those elements to the left of Boron will carry partial positive charge
• Electron affinity increases down the period and decreases down the group
• Lattice energy - the amount of energy required to break apart an ionic lattice
• Lattice energy depends on 2 factors: charge strength and atomic radius
• To determine which molecule has the greatest lattice energy, we must think of charge first, and then think of radius
• For energy to go up from Columbus law, we want charge to go up and radius to go down
• ionization energy trend has exceptions if electron has to be removed from half-filled or completely filled subshells
• First electron affinity is usually negative and second is positive because of electron repulsion
• Metallic chararacter increases to the left and down the group
• Nonmetallic character increases to the right and up the group
• The greater the charge, the greater the lattice energy
• The smaller ions, the greater lattice energy
• electron acceptor should have a high electron affinity.