Module 4-5 Vocab

Element

A pure substance made of only one kind of atom

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds

Atom

Smallest unit of an element that still has properties of that element

Ion

Atom/atom group that has electrical charge because it has gained/lost electron(s)

Electron

Negatively charged particle

Valence Electron

An electron that is found in the outermost shell of an atom and that determines the atom's chemical properties

Nucleus

Center of an atom

Dalton

Unit for measuring mass of atoms and molecules

- Named for John Dalton and his model of an atom

- 1 Dalton = approx. mass of 1 proton or neutron

Lattice

Regular, repeating arrangement of particles in a solid

Molecule

Two or more atoms that are covalently bonded together

Covalent Bond

Chemical bond where atoms share electrons

Ionic Bond

Electrical attraction between oppositely charged ions

- Usually formed when one atom transfers electrons to another

Metallic Bond

Metal atoms bond together and valence electrons are free to move throughout soild

Lewis Structure

A drawing that shows an atom's valence electrons and how they are shared/transferred during bonding

Polymer

Very large molecule made up of many smaller repeating monomers

Monomer

Small, building molecules that join with others to make bigger molecules

Oligomer

Molecule made of few monomers joined together

Physical Change

Can be observed/measured without changing the substance

- Color, density, melting point

Chemical Change

Can change into new substance

- Flammability, rust, reaction to acid

Chemistry is a _______ science.

Central

- can be connected to physics, biology, Earth science and astronomy

What determines what element an atom is?

Atomic number (number of protons)

Atomic Mass

Protons + Neutrons

- Measured in Daltons

How is the Periodic Table organized?

Increases by atomic number

- Rows: periods

- Columns: groups/familes

Atomic Symbols

Element- (X)

Atomic Number- (Z) The number of protons

Mass Number- (A) Number of protons plus neutrons

(This number can change if neutrons change)

Cation

Positively charged ion

- loses electrons

Anion

negatively charged ion

-gained electrons

Crystalline Solid

Particles arranged in regular, repeating pattern

- Salt, quartz, diamond

Amorphous Solid

Particles do not have a regular and repeating pattern

- Glass, many plastics

Empirical Formula

Simplest whole number ratio of elements in a compound

Molecular Formula

A chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms.

Covalent Network Solid

Atoms are connected by covalent bonds in large, continuous network

- diamonds, quartz

- these materials are often very hard and have high melting points

Homogeneous Mixture

Mixture with uniformity throughout

Heterogeneous Mixture

Mixture that is not uniform throughout

Polar

Molecule with uneven distribution of electrical charge giving slightly positive and negative ends

Nonpolar

Molecule where electrical charge is evenly distributed throughout and has no significant positive or negative ends

Electrolyte

Substance that produces ions in water and allows solution to conduct electricity

Nonelectrolyte

Dissolves in water but does not produce ions therefore does not conduct electricity well

Solution

Homogeneous mixture in which one substance is dissolved in another

Solvent

Substance in solution that does the dissolving

- Water in salt water

Solute

Substance that is dissolved in solution

- Salt in salt water

Temperature

Measure of average kinetic energy in a substance

Colligative Properties

Properties that depend on the concentration of solute particles but not on their identity

Aqueas Solution

Solution where water is the solvent.

Intermolecular Forces

forces of attraction between molecules

Chromatography

Methods of separating mixture based on a difference in stationary and mobile movement

Distillation

Method of separating substances based on their different boiling point

Filtration

Method of separating solid from liquid with a filter

Settling

Separation method where heavier parts sink because of gravity

Mixture VS Compound

- Substances are physically combined versus elements are chemically bonded

- both parties keep their properties versus creating new substance

- amount of substance varies verses fixed ratio of elements

Brass; Mixture or Compound?

Mixture

- mixture of copper and zinc because they are not chemically bonded into specific compound

Hydrates

Compounds that have a specific number of water molecules attached to them

- Considered compound because it is a specific ratio, not just a mixture with water

Concentration

The relationship between amount of solute in solution

- Concentrated vs dilute

Factors that affect how much solute can be dissolved in a solution:

1. Temperature (Temp inc, amount dissolved inc)

2. Pressure

3. Nature of substance (like dissolves like)