Unit 1: Chemical Fundamentals

What are isotopes?

Atoms of the same element with different numbers of neutrons and the same number of protons.

What trend is observed for atomic radius across a period?

Atomic radius decreases due to increasing nuclear charge, which pulls electrons closer.

Why does ionization energy increase across a period?

Increased nuclear charge makes it harder to remove an electron.

What is the significance of periodicity in the periodic table?

It explains the repeating patterns of chemical and physical properties across periods and groups.

What are the key differences between ionic and covalent bonding?

Ionic bonding: Transfer of electrons, forms between metals and non-metals.

Covalent bonding: Sharing of electrons, forms between non-metals.

How is the structure of a molecule determined?

By the arrangement of atoms and the type of chemical bonds formed (single, double, or triple).

What are valence electrons, and why are they important?

Electrons in the outermost shell; they determine bonding and chemical reactivity.

How is the relative molar mass of a compound calculated?

Add the atomic masses of all the atoms in the compound.

What is the law of conservation of mass?

Mass is neither created nor destroyed in a chemical reaction.

What is a chemical change?

A process where substances transform into new substances with different properties.

How do you calculate the mass of a product in a chemical reaction?

Use stoichiometry: balance the equation, convert moles to grams using molar masses.

What happens at the boiling point of a substance?

The liquid turns into gas as particles gain enough energy to overcome intermolecular forces.

How do intermolecular forces affect melting and boiling points?

Stronger intermolecular forces result in higher melting and boiling points.

What are the three main states of matter, and how do particles behave in each?

Solid: Particles vibrate in fixed positions.

Liquid: Particles move freely but remain close.

Gas: Particles move rapidly and are widely spaced.

What distinguishes metals from non-metals?

Metals: High conductivity, malleable, ductile, shiny.

Non-Metals: Poor conductivity, brittle, dull.

Why are alkali metals highly reactive?

They have one valence electron, which is easily lost to form a +1 ion.

What trend is observed in Group 1 metals' melting points?

Melting points decrease down the group due to weaker metallic bonds.

What is the significance of successive ionization energies?

They indicate the stability and arrangement of electrons in shells.

How do electron configurations relate to the periodic table?

The periodic table's structure reflects the arrangement of electrons in atomic orbitals.

Why does the ionization energy decrease down a group?

Increased atomic size and shielding effect reduce the attraction between the nucleus and valence electrons.