Chem Bonding

Why do atoms bond?

To achieve a lower energy and more stable electron arrangement

What causes chemical bonding?

Electrostatic attraction between oppositely charged particles.

Define ionic bonding

Electrostatic attraction between oppositely charged ions formed by electron transfer.

Which elements usually form ionic bonds?

Metals and non-metals.

What happens to a metal atom in ionic bonding?

It loses electrons to form a cation.

What happens to a non-metal atom in ionic bonding?

It gains electrons to form an anion.

Why are ionic compounds electrically neutral?

The total positive and negative charge balance out.

What structure do ionic compounds form?

A giant ionic lattice.

Why do ionic compounds have high melting points?

Strong electrostatic attractions between oppositely charged ions.

Why are ionic compounds brittle?

Shifting layers cause ions of the same charge to repel.

When do ionic compounds conduct electricity?

When molten or dissolved in water.

Why don’t solid ionic compounds conduct electricity?

Ions are fixed in position and cannot move.

How does ion charge affect lattice strength?

Higher charges increase electrostatic attraction.

How does ion size affect lattice strength?

Smaller ions form stronger attractions.

Define covalent bonding

Sharing of one or more pairs of electrons between atoms.

Which elements usually form covalent bonds?

Non-metals with similar electronegativities.

What is a single covalent bond?

One shared pair of electrons.

What is a double covalent bond?

Two shared pairs of electrons.

What is a triple covalent bond?

Three shared pairs of electrons.

How does bond order affect bond length?

Higher bond order means shorter bond length.

How does bond order affect bond strength?

Higher bond order means stronger bonds.

Define a polar covalent bond

A bond where electrons are unequally shared due to electronegativity difference.

What causes partial charges (δ+ and δ−)?

Unequal sharing of electrons in polar bonds.

Define a non-polar covalent bond

A bond with equal electron sharing.

What are simple molecular substances?

Substances made of discrete molecules with covalent bonds.

What forces act between simple covalent molecules?

Weak intermolecular forces.

Why do simple covalent molecules have low melting points?

Weak intermolecular forces between molecules.

Why do simple covalent substances not conduct electricity?

They lack free ions or delocalized electrons.

What is a giant covalent structure?

A continuous network of atoms joined by covalent bonds.

Why does diamond have a very high melting point?

Each carbon forms four strong covalent bonds in a giant lattice.

Why is diamond very hard?

Strong covalent bonds in all directions.

Why does diamond not conduct electricity?

No delocalized electrons.

Why does graphite conduct electricity?

Each carbon has one delocalized electron.

Why is graphite soft?

Layers are held together by weak forces.

Why does silicon dioxide have a high melting point?

Strong covalent bonds in a giant structure.

What are London dispersion forces?

Temporary attractions caused by momentary dipoles in all molecules.

What affects the strength of London forces?

The size of the molecule.

What are dipole-dipole forces?

Attractions between permanent dipoles in polar molecules.

What is hydrogen bonding?

Strong intermolecular attraction involving H bonded to N

Why does water have an unusually high boiling point?

Due to hydrogen bonding.

How do ionic and covalent bonding differ in particles involved?

Ionic involves ions; covalent involves molecules or atoms.

Compare melting points of ionic and covalent substances

Ionic generally high; simple covalent generally low.

Compare electrical conductivity of ionic and covalent substances

Ionic conduct when molten or aqueous; covalent generally do not.

What key term explains ionic bonding strength?

Strong electrostatic attraction.

What key term explains low boiling points in covalent molecules?

Weak intermolecular forces.