Periodic Trends

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What are periodic trends?

Periodic trends are patterns in the periodic table that show the variations in certain elemental properties across periods and groups.

How does atomic radius change across a period?

Atomic radius generally decreases across a period from left to right due to increased nuclear charge pulling electrons closer.

What is the trend in atomic radius down a group?

Atomic radius generally increases down a group because of the addition of electron shells.

How does ionization energy change across a period?

Ionization energy generally increases across a period from left to right as atoms hold electrons more tightly.

What happens to ionization energy down a group?

Ionization energy generally decreases down a group since outer electrons are farther from the nucleus and more shielded.

What is electronegativity?

Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

Describe the trend of electronegativity across a period.

Electronegativity generally increases across a period from left to right.

What is the trend in electronegativity down a group?

Electronegativity generally decreases down a group.

Define electron affinity.

Electron affinity is the change in energy when an electron is added to a neutral atom to form a negative ion.

What is the trend of electron affinity across a period?

Electron affinity increases across a period, with some exceptions, due to stronger attraction to the nucleus.

How does electron affinity change down a group?

Electron affinity generally decreases down a group, although there are some exceptions based on specific elements.

What is the trend of metallic character across a period?

Metallic character decreases across a period from left to right as elements become more non-metallic.

How does metallic character change down a group?

Metallic character increases down a group as atoms more readily lose electrons.

Explain the trend of reactivity in alkali metals.

Reactivity increases down the group for alkali metals as ionization energy decreases.

Describe the trend in reactivity among the halogens.

Reactivity decreases down the group for halogens since higher atomic radii reduce the attraction for additional electrons.