PAGE 7 — Periodic Table Basics & PAGE 8 — Periodic Trends

What is a group on the periodic table?

A vertical column of elements.

What do elements in the same group have in common?

The same number of valence electrons → similar chemical properties.

What is a period on the periodic table?

A horizontal row of elements.

What do elements in the same period have in common?

The same number of electron shells.

How many groups are on the periodic table?

18

How many periods are on the periodic table?

7

What happens to atomic radius across a period (left → right)?

It decreases (more protons pull electrons in).

What happens to atomic radius down a group (top → bottom)?

It increases (more electron shells).

What happens to electronegativity across a period?

It increases

What happens to electronegativity down a group?

it decreases

What is the size of atom; increases down, decreases across?

Atomic Radius

What is the attraction for electrons; increases across, decreases down?

Electronegativity

Where are metals located on the periodic table?

On the left side and center.

Where are nonmetals located on the periodic table?

On the right side

Where are metalloids located on the periodic table?

Along the zig‑zag staircase line between metals and nonmetals.

What do metals tend to do with electrons?

Lose electrons to form cations.

What do nonmetals tend to do with electrons?

Gain or share electrons to form anions or covalent bonds.

What do metalloids tend to do with electrons?

They can gain or lose electrons depending on the reaction.

Are metals good conductors?

Yes

• they conduct heat and electricity well.

Are nonmetals good conductors?

No

• they are poor conductors.

Are metalloids good conductors?

They are semiconductors (conduct better than nonmetals, worse than metals).

What is the appearance of metals?

Shiny (luster).

What is the appearance of nonmetals?

Dull

What is the appearance of metalloids?

Shiny or dull, depending on the element.

Are metals malleable and ductile?

Yes

• they can be shaped and stretched.

Are nonmetals malleable or ductile?

No

• they are brittle if solid.

Are metalloids malleable or brittle?

Brittle, like nonmetals.

What type of ions do metals form?

Cations (positive).

What type of ions do nonmetals form?

Anions (negative).

What type of ions do metalloids form?

They can form cations or anions.

What is a key property of metalloids?

They are semiconductors, useful in electronics.

What is atomic radius?

The size of an atom (distance from nucleus to outer electrons).

What happens to atomic radius across a period (left → right)?

It decreases.

Why does atomic radius decrease across a period?

More protons pull electrons closer.

What happens to atomic radius down a group (top → bottom)?

It increases.

Why does atomic radius increase down a group?

More electron shells are added.

Which is larger: a cation or its neutral atom?

The neutral atom (cations shrink).

Which is larger: an anion or its neutral atom?

The anion (anions expand).

Why do cations get smaller?

They lose electrons, reducing electron‑electron repulsion.

Why do anions get larger?

They gain electrons, increasing repulsion and expanding the cloud.

What is electronegativity?

An atom’s ability to attract electrons in a bond.

Why does electronegativity increase across a period?

More protons pull electrons more strongly.

Why does electronegativity decrease down a group?

More electron shells reduce attraction.

How does electronegativity relate to bond type?

• Large difference → ionic

• Small difference → polar covalent

• Equal → nonpolar covalent

How does reactivity change for metals down a group?

Increases (they lose electrons more easily).

Why does metal reactivity increase down a group?

More electron shells → electrons are farther from the nucleus → easier to lose.

Where are the most reactive metals located?

Bottom‑left of the periodic table.

Which group contains the most reactive metals?

Group 1 (alkali metals).

How does reactivity change for nonmetals down a group?

Decreases

Why does nonmetal reactivity decrease down a group?

Larger atoms have weaker pull on electrons → harder to gain electrons.

Where are the most reactive nonmetals located?

Top‑right (excluding noble gases).

Which group contains the most reactive nonmetals?

Group 17 (halogens).

Why are halogens highly reactive?

They only need one electron to fill their valence shell.

How does atomic size relate to metal reactivity?

Bigger atoms → more reactive metals.

How does atomic size relate to nonmetal reactivity?

Smaller atoms → more reactive nonmetals.