Periodic Table Periods Atoms in a period have the same number of energy levels.

Periodic Table Groups Many groups have special names that describe their characteristics. Atoms in a group have same number of valence electrons so they behave similarly. Roman numerals represent the number of valence electrons.

Terms to Know Cations refer to the elements that lose electrons and form a positive ion. Cations refer to the elements that lose electrons and form a positive ion. Anions refer to the elements that gain electrons and form a negative ion. Anions refer to the elements that gain electrons and form a negative ion.

Alkali Metals All form +1 cations Very reactive with water Highly reactive in general

Alkaline Earth Metals All form +2 Cations All form +2 Cations Somewhat reactive with water Somewhat reactive with water Highly reactive with acids. Highly reactive with acids.

Halogens All form -1 Anions Aggressive Oxidizers Used in Halogen bulbs.

Noble Gases Non-reactive Non-reactive Fulfilled Octet Rule—have 8 valence electrons in the outer most energy level and considered stable. Fulfilled Octet Rule—have 8 valence electrons in the outer most energy level and considered stable.

Other Groups Group 13 (IIIA) – Boron Family Group 13 (IIIA) – Boron Family Form +3 Cations Form +3 Cations Group 14 (IVA) – Carbon Family Group 14 (IVA) – Carbon Family Form + 4 Cations or Anions Form + 4 Cations or Anions Group 15 (VA) – Nitrogen Group Group 15 (VA) – Nitrogen Group Form -3 Anions Form -3 Anions Group 16 (VIA) – Oxygen Family Group 16 (VIA) – Oxygen Family Form -2 Anions Form -2 Anions

Periodicity When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. An important consequence is that the elements with similar chemical and physical properties end up in the same column. An important consequence is that the elements with similar chemical and physical properties end up in the same column. Trends on the periodic table govern how elements behave chemically. Trends on the periodic table govern how elements behave chemically. All elements are unique, but follow these trends….generally. All elements are unique, but follow these trends….generally.

Atomic Size/Atomic Radius Atomic radius is ½ the distance between the nuclei of identical atoms that are bonded together. Group Trend – size INCREASES as you move down (added energy levels; electrons farther from nucleus). Period Trend – size DECREASES as you move left to right (more protons and electrons pulling harder on one another). Due to increasing energy levels and shielding by inner electrons. Inner electrons shield the outermost electrons from the nucleus.

Atomic Size Cont.

Which atom has the larger radius? Which atom has the larger radius? BeorBa CaorBr Ba Ca Examples

Ionic Size/Ionic Radius Ionic Radius is the relative size of the most common ion of an atom. Group Trend – INCREASE top to bottom due to shielding. Cations are always smaller than their neutral atom Loss of electrons increase attraction Anions are always bigger than their neutral atom. Gain of electrons decrease attraction Period Trend – DECREASE left to right.

Electronegativity Electronegativity is a measure of the ability of an atom in a chemical compound to attract electrons when they are chemically combined with atoms of another element. Electronegativity is a measure of the ability of an atom in a chemical compound to attract electrons when they are chemically combined with atoms of another element. Group Trend – DECREASE as you move down due to increasing number of energy levels. Group Trend – DECREASE as you move down due to increasing number of energy levels. Period Trend – INCREASE from left to right right due to switch from cat ions to anions. Period Trend – INCREASE from left to right right due to switch from cat ions to anions. Fluorine has an electronegativity of 4.0, everything below and to the left is lower. Fluorine has an electronegativity of 4.0, everything below and to the left is lower.

Electronegativity

Electronegativity

Ionization Energy Ionization Energy is the energy required to overcome the attraction of the protons and remove one electron from a neutral atom of an element. Ionization Energy is the energy required to overcome the attraction of the protons and remove one electron from a neutral atom of an element. The energy required to remove the 1 st outermost electron is call the 1 st ionization energy. And the energy for the 2 nd outermost electron to be removed is called 2 nd ionization energy. The energy required to remove the 1 st outermost electron is call the 1 st ionization energy. And the energy for the 2 nd outermost electron to be removed is called 2 nd ionization energy. Atoms may have 2 nd or 3 rd ionization energies depending on number of valence electrons and adherence to octet rule. Atoms may have 2 nd or 3 rd ionization energies depending on number of valence electrons and adherence to octet rule.

Ionization Energy Group Trend – ionization energy DECREASES as you move down (electrons further from the pull of the nucleus are easier to remove). Period Trend – ionization energy INCREASES as you move left to right (greater attraction of the nucleus for electrons).

Ionization Energy Cont.

Which atom has the higher 1st I.E.? Which atom has the higher 1st I.E.? NorBi BaorNe N Ne Examples

Summary of Periodic Trends