Transcript Unit 4: Periodic Table Trends ppt

Periodic Table
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
.
1.
2.
3.
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
Left to Right
Increases
(larger size atom)
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
Left to Right
Decreases
(less energy
released)
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)
Anions
-gained electron(s)
(Nonmetals)
Smaller
(compared to
original atom)
Larger
(compared to
original atom)