Trends and Similarities

Trends of the Periodic Table:
At the conclusion of our time together, you should be able to:
1. Give a trend across and down the Periodic
Table for metallic characteristics, reactivity, atomic radius and ion radius, electron affinity, ionization energy, and electronegativity.
2. Pick the element with the higher trend above from a list of several elements

Trends In The Periodic Table:
Ionization Energy
Atomic Radius
Electron Affinity
Electronegativity, Etc.

Periodic Trends
Try to determine the trends by looking at the charts on p. 11.

Atomic Radius
½ the distance between the nuclei of two identical atoms that are bonded together.

Atomic Radius Trends

.
Atomic Radius Trend
Explanation
2.
3.
1.
Electron-electron repulsion makes radius larger, very weak interactions.
Proton – electron attraction = smaller atom
Energy level, n (distance from the nucleus), as they go higher = larger atom

Atomic Radius Trends
Top to Bottom
Increases
(larger size atom)
Left to Right
Decreases
(smaller size atom)

Electron Affinity
The energy change that occurs when a neutral atom acquires an electron.
Energy is released from the atom.
Atoms that really want another electron tend to release more energy.

Electron Affinity Trends
Top to Bottom
Decreases
(less energy released)
Left to Right
Increases
(more energy released)
Noble Gases = 0

Ionization Energy
The energy (effort) required to remove one electron from a neutral atom.

Ionization Energy Trends

Ionization Energy Trend
Explanation
The closer to the nucleus (smaller atomic radius), the harder to take an electron away.
The farther away from the nucleus (larger atomic radius), the easier it is to take an electron away.

Ionization Energy Trends
Top to Bottom Left to Right
Decreases Increases

Electronegativity
A measurement of the ability of an atom in a chemical compound to attract electrons.
(how strongly an atom holds onto its own electrons and how strongly it needs another electron)
 Most electronegative element – Fluorine (F)
 It is assigned the number 4
 All other values are based on this value.

Electronegativity Trends

Electronegativity Trends
Top to Bottom Left to Right
Decreases Increases

Ionic Radius
1.
Cations lose electrons, therefore they tend to be
Positive Ions - Metals
2.
Anions gain electrons, therefore they tend to be
Negative Ions - Nonmetals

Ionic Radius Trends

Ionic Radius Trends
Cations
-lost electron(s)
(Metals)
Smaller
(compared to original atom)
Anions
-gained electron(s)
(Nonmetals)
Larger
(compared to original atom)