156 terms

2017 Chemistry Semester 1 Exam Review Set

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chemical bond
attractive force that holds together the atoms in a molecule.
basic types are ionic, covalent and metallic
element
a pure substance made up of only one type of atom; it cannot be broken down into simpler substances
compound
a pure substance that contains atoms of two or more different elements combined in a fixed ratio.
molecule
a pure substance made up of two or more atoms which are combined in a constant ratio and held together by chemical bonds. The substance may have two of the same type of atoms or two different types of atoms.
physical change
process in which some properties of a substance change, but the substance is still the same. Liquid water freezing to ice is one example.
chemical reaction
a process in which existing bonds are broken and new bonds are formed, producing substances which are different from the starting materials.
reactant
the substance that you start with in a chemical reaction
product
the new substance that are formed in a chemical reaction
chemical equation
A representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products
precipitate
a solid that forms as a result of mixing two solutions
chemical formula
A combination of element symbols which shows how many and which type of elements are in a compound.
indicator
a substance that is added to a reaction to show the presence or amount of another material, or to show the progress of a reaction (an example is an acid-base indicator like litmus paper or phenlophthalein).
catalyst
a substance that speeds up a chemical reaction, but is itself not permanently changed by the reaction.
covalent bond
chemical bond formed when two atoms share one or more electrons.
ionic bond
chemical bond formed when one atom gains and a second atom loses electrons.
single replacement
a reaction in which one element takes the place of another element in a compound
double replacement
a reaction where two reactants exchange places in ionic compounds
decomposition
a reaction where the compound breaks down to form two or more simpler substances
combination
a reaction in which two or more substances combine to form a new compound. Also called synthesis.
evidence of a chemical reaction
color change, energy change (temperature), a gas is produced (bubbling), a precipitate forms
endothermic
a reaction that absorbs energy more energy than it releases
(feels cold if touched)
exothermic
A reaction that releases more energy than it absorbs (feels hot if touched)
coefficient
regular sized numbers in front of a chemical formula that indicate how many copies of that material are present in a chemical equation
subscript
small numbers written after and to the lower right of atoms or polyatomic ions that indicate how many copies of that atom or ion are in the chemical formula
photochemical
Reactions that only take place in the presence of light. These reactions are often synthesis or decomposition reactions and depend on specific wavelengths of light to occur. Examples are the formation of ozone or smog and the decomposition of chlorine in swimming pools.
neutralization
A reaction in which an acid reacts with a base and forms water and a "salt"
salt
Ionic compounds that form from the ions left behind when an acid neutralizes a base.
HX (acid) + YOH (base) →
H⁺ + X⁻ + Y⁺ + OH⁻ (ions in solution) →
HOH (water) + XY (salt)
acid
A molecule that releases Hydrogen Ions (H⁺) when dissolved in water. These substances taste sour, react with metals and carbonates to form Hydrogen gas (H₂), and turn litmus paper red.
base
A substance that releases Hydroxide Ions (OH⁻) when dissolved in water. These substances taste bitter, feel slippery or soapy, react with oils and grease, and turn litmus paper blue.
combustion
A chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat and light. Reactions with hydrocarbons produce carbon dioxide and water.
2.4 x 10⁴
24,000
4.386 x 10⁷
43,860,000
3.05 x 10²
305
6.000032 x 10⁶
6,000,032
8.75 x 10⁵
875,000
7.1 x 10⁻⁶
0.0000071
4.39 x 10⁻⁷
0.000000439
9.0 x 10³
9,000
1.03 x 10⁸
103,000,000
5.11 x 10¹⁰
51,100,000,000
1.6 x 10¹
16
8.49 x 10⁻²
0.0849
1.0 x 10⁻³
0.001
1.25 x 10⁻⁴
0.000125
3.7 x 10⁻⁵
0.000037
exponent
the small number at the top right of a number or variable
scientific notation
#.### x10^
The way scientists write very large or very small numbers
standard form
a number written in it's regular form, "normal"
observation
using one or more of the senses to gather information (taste, touch, see, hear or smell)
inference
An idea, intuition or understanding based on data
hypothesis
A testable If, Then, Because prediction
variable
a factor in an experiment that can change, either intentionally (manipulated) or unintentionally (uncontrolled)
experimental control
a standard against which other conditions can be compared in a scientific experiment
experiment
the act of conducting a controlled test or investigation
data
facts, figures, and other evidence gathered through observations
analysis
the careful examination of data looking for patterns or trends that have meaning
conclusion
a summary of whether the results of the experiment support the hypothesis
scientific
an organized way to ask questions using carefully developed methods and procedures
accuracy
how close a measured value is to the true or real value
precision
how close a series of measurements are to one another
correlation
mutual relationship between two factors
significant
an observed effect so large that it would rarely occur by chance
measurement
obtaining a number that tells the amount of something
estimate
to make a careful guess related to the number, amount, or size
theory
A unifying explanation for a broad range of hypotheses and observations that have been supported by testing
law
An observation that happens every time under a certain set of conditions
physics
The study of matter and energy and the interactions between the two through forces and motion.
chemistry
The study of the properties of matter and how matter changes
Precision
Describes the closeness, or reproducibility, of a set of measurements taken under the same conditions.
Accuracy
A description of how close a measurement is to the true value of the quantity measured.
Significant Digit
The digits on either side of the decimal point that seem reasonably certain to have been measured (not zeros that are place holders).
Scientific Notation
A mathematical method of writing numbers using powers of ten to express really large or small numbers.
Factor-Label Process
A chemistry problem solving tool that includes identifying what you have, what you need, and conversion factors in order to express an answer in a desired unit.
numerator
The factor-label pair written above the line in dimensional analysis.
denominator
The factor-lbel pair writtenbelow the line in dimensional analysis.
Chemistry
The study of matter and how it changes.
Matter
Anything that has mass and takes up space.
Mass
Amount of matter in an object.
Volume
How much space an object takes up
Chemist
Scientist that studies matter and how it changes
Qualitative
Describing the characteristics of something without using numbers
Quantitative
Describing something using measurements and numbers
Scientific Method
an organized process for investigating the world around us
Hypothesis
A "testable" If, then, because prediction in science
Variable
A condition or a characteristic of matter that is measured or controlled in an experiment.
Independent Variable
a variable that is intentionally changed in an experiment
(manipulated variable)
Dependent Variable
a variable that is measured in an experiment
(response variable)
Theory
A widely accepted hypothesis that has been tested many times which "best explains" and predicts future activities
Technology
The application of science to help people improve their lives.
Scientific Notation
writing or displaying numbers in terms of a decimal number "a" between 1 and 10, multiplied by a power of 10 in the form
"a" x 10ⁿ
Superscript
A number that is written just above the writing line.
Accuracy
How close a measurement is to the correct or accepted value
Precision
how close a measurement is to other measurements of the same thing
Significant Figure
a meaningful digit in a measured value.
Unit
a standard amount used for measuring
Meter
The SI unit for measuring length
Gram
The SI unit for measuring mass
Liter
The SI unit for measuring volume
Kelvin
The SI unit for measuring temperature
Degree Celsius (°C)
A unit for measuring temperature often used in metric measuring
Unit Conversions
The process of changing a measurement from one unit to another.
Conversion Factor
a ratio that shows two units that are equal two one another
Derived Unit
a measurement unit created by multiplying or dividing other units
Density
the mass of a sample matter divided by its volume
2008 NIST SI Units List
The National Institute of Standards and Technology
http://physics.nist.gov/cuu/pdf/sp811.pdf
page 7
physical property
a characteristic of a substance that can be observed without changing the substance.
state
the physical form of a substance; solid, liquid, gas, or plasma
solid
A state of matter that has definite shape and volume.
liquid
a state of matter that has a definite volume but no definite shape.
chemical reaction
The chemical changes involved when one or more substances react, forming one or more different substances.
chemical change
A change in matter that produces one or more new substances.
homogeneous
A mixture in which all of the individual substances are evenly mixed throughout.
gas
a state of matter that has no definite volume or shape.
chemical property
A characteristic that describes how a substance changes into one or more different substances.
substance
A single kind of matter that is pure; has fixed composition and definite chemical and physical properties.
mixture
two or more substances mixed together.
heterogeneous
A mixture in which one or more substances are unevenly mixed throughout.
solution
A homogeneous mixture of one or more solutes dissolved in a solvent; can be solid, liquid or gas.
solute
A substance that is dissolved in a solvent to make the solution.
alloy
a solid solution containing metals.
aqueous
solution in which the solvent is water.
solvent
the substance that a solute is dissolved in; usually the substance in a solution that is present in the greatest amount.
physical change
A change that affects the appearance but not the chemical makeup of a substance.
energy
Ability to do work or to produce heat.
proton
A subatomic particle that has a positive charge and that is found in the nucleus of an atom.
neutron
A subatomic particle that has no charge and that is found in the nucleus of an atom.
electron
A negatively charged particle that is found outside the nucleus of an atom.
charge
a certain amount of electricity. Is also a measure of the positive or negative state of an ion.
nucleus
A region with protons and neutrons that is located at the center of an atom and contains most of the atom's mass.
chemical bond
An attraction between two atoms resulting from the sharing of or transfer of electrons.
element
A pure substance made of only one kind of atom.
atomic number
Number of protons in an atom.
atom
the smallest particle of an element having the chemical properties of the element.
chemical symbol
A one or two letter representation of an element.
periodic table
A chart of the elements organized by atomic number and electron arrangement that shows the repeating pattern of their properties.
metal
Elements on the left side of the periodic table; often shiny solids that are good conductors of heat and electric current.
nonmetal
Elements on the upper right side of the periodic table that are generally gases or dull solids; poor conductors of heat and electricity.
semimetal
Elements along the staircase of the periodic table that have some characteristics of both metals and nonmetals.
monatomic
existing as single atoms or ions.
diatomic
A molecule consisting of pairs of bonded atoms.
(remember HI BrONClF)
polyatomic
existing as groups of three or more bonded atoms.
subscript
A number written slightly below and to the right of a chemical symbol that shows how many atoms of an element are in a compound.
compound
A molecule made up of atoms of two or more different kind of elements joined by chemical bonds.
chemical formula
A group of symbols that represents the number and kind of atoms in a substance.
Mole (abbreviated Mol)
The SI unit used to measure the amount of a substance. Is equal to 6.02 X 10²³ particles of any substance.
Avogadro's number
number of "representative particles" in a mole, 6.02 X 10²³
representative particles
Refers to the type of particle present in a substance: usually atoms, molecules, or formula units.
molecule
two or more atoms held together by covalent bonds
formula unit
The lowest whole-number ratio of ions in an ionic compound
molar mass
the mass in grams of 1 mol of a substance
gram atomic mass
the mass of one mole of an element, found as the "atomic mass" on the periodic table, expressed as grams per mole (g/mol)
gram formula mass
the sum of the mass of all the atoms in one mole of an ionic compound, expressed as grams per mole (g/mol)
gram molecular mass
The sum of the mass of all the atoms in one mole of a particular molecule, expressed as grams per mole (g/mol)
empirical formula
a formula showing the lowest whole number ratio of atoms in a compound
percent composition
the percent by mass of each element in a compound
"Molar Express"
tool used for setting up Chemistry problems
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