More Periodic Table Trends (Page 4 of 4) in pdf

More Periodic Table Trends Page 4

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Electronegativity

electronegativity: indicates how strongly an atom attracts electrons in a chemical

bond

Thought POE: How does electronegativity vary within groups and periods?

Trend Down

a Group

The further down you go, the greater the distance

decreases

between the electrons on the outermost shell, so

the hold on the nucleus is decreasing

Trend Across

a Period

The electrons are held closer to the nucleus, so

increases

any shared electrons are going to have a stronger

pull towards the nucleus than if the electrons were

held farther from the nucleus

Unlike ionization energy, electronegativity is not an amount of energy. Nor is it a property of an

atom that can be directly measured.

Fluorine is the most electronegative element, with an electronegativity of 4.0.

All other

electronegativity values are assigned relative to fluorine’s. The least electronegative elements are

in the lower left corner of the periodic table. Both cesium and francium have electronegativities

of 0.7. If a cesium atom and a fluorine atom were to form a chemical bond, the atom with the

higher electronegativity–the fluorine atom-would more strongly attract the bond’s electrons.

Conductivity

Thought POE: How does conductivity vary within groups and periods?

Trend Down

Conductivity is a metallic property, it increases

a Group

increases

down a table

Trend Across

it is a metallic property, it decreases as you go

a Period

decreases

across

More Periodic Table Trends Page 4