Chapters 1, 2, 3, and 4 Chemistry Exam

Voltality

Evaperation

Steps of Scientific Method

1.) Making an Observation 2.) Making a Hypothesis 3.) Preforming an Experiment

Ernest Rutherford

1911-Explained the nuclear atom. Atom has a dense center of positive charge called the nucleus. Electrons travel around the nucleus at a relatively large distance. A proton has the same magnitude of charge as the electron, but its charge is positive

Rutherford and Chadwick

1932-Most nuclei also contain a neutral particle called the neutron. A neutron is slightly more massive than a proton but has no charge

Mixtures

2 of more pure substances Have variable composition. Examples Wood, wine, coffee Can be separated into pure substances: elements and/or compounds.

Chemical Change

A given substance becomes a new substance or substances with different properties and different composition. Example: Bunsen burner (methane reacts with oxygen to form carbon dioxide and water)

Hypothesis

A possible explanation for an observation

Compound

A substance composed of a given combination of elements that can be broken down into those elements by chemical methods. Examples: Water (H2O), carbon dioxide (CO2), table sugar (C12H22O11) A compound always contains atoms of different elements. A compound always has the same composition (same combination of atoms).

element

A substance that cannot be broken down into other substances by chemical methods. Examples: Iron (Fe), aluminum (Al), oxygen (O2), and hydrogen (H2) All of the matter in the world around us contains elements.

Pure Substances

Always have the same composition. Either elements or compounds. Examples: Pure water (H2O), carbon dioxide (CO2), hydrogen (H2), gold (Au)

Theory (Model)

An attempt to explain why it happens. Set of tested hypotheses that gives an overall explanation of some natural phenomenon

Matter

Anything occupying space and having mass. Matter exists in three states. Solid Liquid Gas

Isotopes

Atoms with the same number of protons but different numbers of neutrons. Show almost identical chemical properties; chemistry of atom is due to its electrons. In nature most elements contain mixtures of

Distillation

Boiling Point

Physical Change

Change in one or more physical properties of a substance, not in its chemical composition. Example: Boiling or freezing water

Physical Properties

Characteristics that are directly observable and unique to a substance. Examples: Odor, color, volume, state (s, l, or g), density, melting point, and boiling point

Adherence to a surface

Chromatography

Heterogeneous Mixture

Consists of visibly distinguishable parts. Contains regions that have different properties from those of other regions. Examples: Oil and vinegar dressing Sand stirred into water

Allotropes

Different forms of a given element. Example: Solid carbon occurs in three forms. Diamond Graphite Buckminsterfullerene

Physical Properties of Metals

Efficient conduction of heat and electricity Malleability (they can be hammered into thin sheets) Ductility (they can be pulled into wires) A lustrous (shiny) appearance

Metalliods

Exhibit a mixture of metallic and non-metallic properties

Density

Mass of substance per unit volume of the substance. Common units are g/cm3 or g/mL

Volume

Measure of the amount of 3-D space occupied by a substance. SI unit = cubic meter (m3) Commonly measure solid volume in cm3. 1 mL = 1 cm3 1 L = 1 dm3

Mass

Measure of the amount of matter present in an object

Dalton's Atomic Theory

Most natural materials are mixtures of pure substances. Pure substances are either elements or combinations of elements called compounds. A given compound always contains the same proportions (by mass) of the elements Elements are made of tiny particles called atoms All atoms of a given element are identical The atoms of a given element are different from those of any other element

JJ Tomson Theory

Postulated the existence of electrons using cathode-ray tubes. The atom must also contain positive particles that balance exactly the negative charge carried by particles that we now call electrons

Scientific Method

Process that lies at the center of scientific inquiry

Measurement

Quantitative observation. Has 2 parts - number and unit. Number tells comparison. Unit tells scale

Wiliam Tomson Theory

Reasoned that the atom might be thought of as a uniform "pudding" of positive charge with enough negative electrons scattered within to counterbalance that positive charge

Homogeneous Mixture

Same throughout. Consists of visibly indistinguishable parts. A solution. Does not vary in composition from one region to another. Examples: Air around you Brass Table salt stirred into water

Filtrations

Separates a liquid from a solid

nucleus

Small compared with the overall size of the atom. Extremely dense; accounts for almost all of the atom's mass

Filtration

State of Matter

Law

Summarizes what happens

Fahrenheit Celsius Kelvin

Systems of Tempurature

Scientific Notation

Technique used to express very large or very small numbers. Expresses a number as a product of a number between 1 and 10 and the appropriate power of 10

Chemistry

The science that deals with the materials of the universe and the changes that these materials undergo

Gas

The water molecules are far apart and move randomly Has no fixed volume or shape. Takes the shape and volume of its container. Examples: Air, helium, oxygen

Solid

The water molecules are locked into rigid positions and are close together Rigid. Has a fixed volume and shape. Examples: Ice cube, diamond, iron bar

Liquid

The water molecules are still close together but can move around at some extent Has a definite volume. Assumes shape of container. Examples: Gasoline, water, alcohol, blood

Electrolysis of Water

Water decomposes to hydrogen and oxygen gases

Groups or Families

elements in the same vertical columns; have similar chemical properties

Chemical Formulas

expresses the types of atoms and the number of each type in each unit (molecule) of a given compound

Neutrons

found in the nucleus; no charge; virtually same mass as a proton

Protons

found in the nucleus; positive charge equal in magnitude to the electron's negative charge

Electrons

found outside the nucleus; negatively charged It is the number of electrons that really determines chemical behavior

Periods

horizontal rows of elements

Science

is a framework for gaining and organizing knowledge

Anions

negative ions -ide

Cations

positive ions

Periodic Table

shows all of the known elements in order of increasing atomic number