Stage 1 - Atomic Structure and Bonding

SACE - Stage 1 Chemistry

Atomic Radii

The average distance from the centre of the nucleus to the boundary of the valence shell.

Electronegativity

The tendency of its atoms to attract electrons from other atoms.

As Electronegativity increases…

Atomic Radii decreases across the period.

As Electronegativity decreases

Atomic Radii increases across the period.

Polar covalent bond

An uneven share of electrons.

Non-polar covalent bond

An even share of electrons.

When an atom loses electrons…

It forms cations.

When an atom gains electrons…

It forms anions

How to determine if molecule is polar?

* Electronegativity difference is above 0.5.
* Nucleus cloud charge is unbalanced.

How to determine if molecule is non-polar?

* Electronegativity difference is below 0.5.
* Nucleus cloud charge is balanced.

Cations

Positively charged ions.

Anions

Negatively charged ions.

Proton

Positively charged subatomic particle.

Electron

Negatively charged subatomic particle.

Neutron

Neutral charge subatomic particle.

Energy level

The specific amount of energy an electron has.

Excited state

a state in which an atom has more energy than it does at its ground state.

Ground state

The lowest energy state of an atom.

Isotope

Atoms of the same element that have different numbers of neutrons.

Valence electrons

Electrons on the outermost energy level of an atom.

Valence shell

Outermost electron shell.

Metallic Bonding

the chemical bonding that results from the attraction between metal cations and the surrounding sea of electrons.

Ionic Bonding

Chemical bonding that results from the electrical attraction between non-metals and metal.

Covalent Bonding

Involves the sharing of electrons between non-metals.

Lattice

A repeating arrangement of atoms in a solid.

Two properties of metal

* Ductility.
* Conduct electricity.

Three properties of ionic compounds

* High melting points
* High boiling point
* Soluble in water

Three properties of covalent compounds

* Low melting points
* Poor electrical conductivity
* Various colour

What does Bohr’s Law state?

Electrons don’t absorb energy or emit energy from the nucleus, unless they transition or jump from orbits.

Why are metals ductile?

They are able to be drawn out into a thin wire because the electrons are free to move which surround the cations.

Molecule

A neutral group of atoms joined together by chemical bonds.

Intermolecular Bonding

Attractive forces between molecules that determines physical properties.

Intramolecular Bonding

Bonding forces within molecules that determines chemical properties.

Dispersion Forces

A temporary attraction of one molecule’s nuclei for the electrons in neighbouring molecules.

Temporary Dipole-Dipole

A result of an uneven distribution of electrons in one neighbouring molecule that results in an induced dipole.

Dipole-Dipole Interaction

An attraction that results from the partially positive end of a polar molecule with a partially negative end of an adjacent molecule.

Hydrogen Bonding

The strongest form of dipole-dipole interaction that results from a partially positive Hydrogen with a partially negative Nitrogen, Oxygen, and Flourine.

3 types of intramolecular bonds

* Ionic Bonding
* Covalent Bonding
* Metallic Bonding

3 types of intermolecular bonds

* Dispersion Forces
* Dipole-Dipole Interaction
* Hydrogen Bond

Nanomaterial

Substances composed of particles ranging from 1-100nm.

Electrolyte

An aqueous solution which produces ions to conduct electricity.

Polyatomic Ion

A group of atoms that have charge (covalent).

What’s the difference between ion and atom?

Atom is electrically neutral, and ion is electrically charged due to loss or gain of electrons.

Relative Atomic Mass

The average mass of all naturally occurring isotopes of the element, relative to the mass of carbon-12.

What does VSEPR stand for?

Valence Shell Electron Pair Repulsion.

What is common with atomic number?

No. of protons and electrons in an atom.

How to calculate neutrons?

Mass number-atomic number.

Thermal Conductivity

Ability to conduct or transfer heat energy.

Electrical Conductivity

Ability to conduct or transfer electrical charge.

Melting Point

The temperature at which a substance changes state, from solid to liquid.

Boiling Point

The temperature at which liquid boils and turns into gas (vapour).

Density

The density of a substance is its mass per unit volume.