Chemistry Definitions and Notes

This set of flashcards covers key definitions and concepts in chemistry.

Element

A pure substance made of only one type of atom that cannot be broken down into simpler components.

Compound

A substance formed when two or more different elements chemically combine and cannot be separated physically.

Mixture

Combinations of two or more substances physically mixed together that can be separated by physical means.

Molecule

A group of atoms bonded together.

Isotope

Different atoms of the same element that have the same number of protons but a different number of neutrons.

Ion

Atoms or groups of atoms that have either a positive or negative charge.

Ionic Bond

A strong electrostatic attraction between oppositely charged ions.

• Resulting in a giant lattice structure of regular arrangement of alternative positive and negative ions

• High boiling and melting point because of strong electrostatic bonds, so it requires a lot of energy to break bonds

• Good electrical conductivity when aqueous or molten because they have mobile ions

• Poor electrical conductivity when solid because ions are stuck in place

Covalent Bond

A bond formed when a pair of electrons is shared between two atoms leading to noble gas electronic configuration.

Simple Covalent Molecules

• Single, double, and triple bonds

• Low melting and boiling points because of a weak intermolecular forces so requires less energy to break bonds

• Most our gases or liquids at RTP

• Poor electrical conductivity because there are no free moving electrons or ions. They are electrically neutral

Giant Covalent Structures

Large structures linked by strong intramolecular forces. The different structure and bonding of diamond and graphite make them have different physical properties.

Diamond Giant Covalent Structure

• Forms tetrahedral network with four neighboring carbon atoms

• Hard and used for cutting tools

• No free electrons to carry charge

• High melting and boiling point

• Non-conductivity

Silicon(IV) Oxide Giant Covalent Structure

• Forms tetrahedral network with each silicon atom bonding to four oxygen atoms

• Hard

• No free electrons to carry charge

• High melting and boiling point

• Non-conductivity

Graphite Giant Covalent Structure

• Forms layers of hexagonal rings of carbon atoms with three bonds with adjacent carbon atoms

• Slippery layered structure due to weak intermolecular forces, and used as lubricant

• Layers contain delocalized electrons so it can conduct electricity, and used as electrodes

Metallic Bonding

Electrostatic attraction between positive ions in a metallic lattice and a sea of delocalized electrons.

• Good electrical conductors

Metal ions can slide past each other while the metallic bond remains.

• Malleable: Easily shaped or flattened

• Ductile: Stretched into thin wires

Molecular Formula

The number and type of different atoms in one molecule.

Empirical Formula

The simplest whole number ratio of different atoms or ions in a compound.

Electrolysis

The decomposition of an ionic compound by the passage of an electric current in a molten or aqueous solution.

Activation Energy

The minimum energy that colliding particles must have to react.

Catalyst

A substance that increases the rate of reaction and is unchanged at the end of the reaction.

Redox Reactions

Reactions that involve simultaneous oxidation and reduction.

Oxidizing Agent

A substance that oxidizes another and is itself reduced.

Reducing Agent

A substance that reduces another and is itself oxidized.

Strong Acid

An acid that is completely dissociated in aqueous solution.

Weak Acid

An acid that is partially dissociated in aqueous solution.

Hydrated Substance

A substance that is chemically combined with water.

Anhydrous Substance

A substance containing no water.

Homologous Series

A family of similar compounds that have similar chemical properties due to the same functional group.

Structural Isomers

Compounds with the same molecular formula but different structural formulae.

Polymer

Large molecules built up from many smaller molecules called monomers.

Saturated Solution

A solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature.