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