Periodic Table Revisited Chapter 14: Periodic Table Revisited

Classifying the Elements by Configuration: Chapter 14.1 1. The noble gases: Inert gases Outmost s and p sublevels are filled. Example: Helium: 1s2 Neon: 2s2, 2p6

Classifying the Elements by Configuration: Chapter 14.1 2. The Representative Elements: Outermost s and p sublevels are only partially filled. Group A elements Examples: 1A: alkali metals 2A: alkaline earth metals 7A: Halogens Group # equals outermost electrons

Classifying the Elements by Configuration: Chapter 14.1 Examples: Group 1A: Na: 1s2, 2s2, 2p6, 3s1 Group 2A: Mg: 1s2, 2s2, 2p6, 3s2 Group 7A: F: 1s2, 2s2, 2p5

Classifying the Elements by Configuration: Chapter 14.1 3. Transition Metals: Metallic elements where s sublevel and d sublevel contain electrons. Group B elements 4. Inner Transition Metals: Metallic elements where outermost s and f sublevels contain electrons.

Periodic Trends: Chapter 14.2 1. Atomic Radius One half the distance between the nuclei of two like atoms in a diatomic molecule. Group Trend: Generally increases as you move down a group Periodic Trend: Decreases as you move from left to right.

Atomic radius vs. Atomic number

Periodic Trends: Chapter 14.2 2. Ionization Energy: The energy needed to remove an electron from a gaseous atom. Group Trend: Energy needed generally decreases as you move down a group Electrons are farther from the nucleau Shielding effect

Periodic Trends: Chapter 14.2 Periodic Trend (ionization energy cont. ) As you move from left to right across a period, ionization energy generally increases. Increase in atomic # means a stronger attraction of the positive nucleus to the electrons.

Ionization Energy vs. Atomic Number

Periodic Trends: Chapter 14.2 3. Ionic Size: The size of the ion as it gains (non-metals) or loses (metals) electrons. Group Trend: Positive Ions (cations/metals) and Negative Ions (anions/ nonmetals) increase in ionic size as you move down a group. Periodic Trend: Cations and Anions generally decrease as you move across a period.

Periodic Trends: Chapter 14.2 4. Electronegativity: the affinity of an atom for electrons- its tendency to attract electrons Group Trends: As you move down a group electronegativity decreases (Fr = least electronegative) Electrons are farther from the nucleus Shielding effect.

Periodic Trends: Chapter 14.2 Electronegativity cont. Periodic Trends: As you move across a period, electronegativity increases. ( F = most electronegative element) Because of smaller atomic radius and ionic size

Electronegativity vs. Atomic Number

Periodic Trends: Chapter 14.2 5. Metallic Character: The metallic character of an element can be defined as how readily an atom can lose an electron. Group Trend: as you move down a group, metallic character increases Fr- the most metallic element Periodic Trend: as you move from left to right across a period, metallic character decreases.