Glossary of Exit Level TAKS Science Objective 4

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What is density?
mass per unit volume
What is viscosity?
the property of a fluid that resists the force tending to cause the fluid to flow.
What is buoyancy?
the power of supporting a body so that it floats; upward pressure exerted by the fluid in which a body is immersed
What is the density of water?
1.0 g/mL or 1.0 cm3
What are the units for density?
g/mL or cm3
What does soluble mean?
capable of being dissolved or liquefied
What is temperature?
A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale
What is pressure?
force per unit area
What is an ionic bond?
the electrostatic bond between two ions formed through the transfer of one or more electrons
What is a covalent bond?
the bond formed by the sharing of a pair of electrons by two atoms
What is a solution?
a homogeneous, molecular mixture of two or more substances
What is a solute?
the substance dissolved in a given solution
What is an element?
one of a class of substances that cannot be separated into simpler substances by chemical means
What is an atom?
the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element
What is a compound?
composed of two or more atoms or elements
What is a mixture?
an aggregate of two or more substances that are not chemically united and that exist in no fixed proportion to each other.
What is a homogeneous mixture?
any combination of substances that has uniform composition and properties; a mixture that is uniform throughout
What is a heterogeneous mixture?
any combination of substances that does not have uniform composition and properties; a mixture of physically distinct substances with different properties
What is a liquid?
composed of molecules that move freely among themselves but do not tend to separate like those of gases
What is a solid?
having relative firmness, coherence of particles, or persistence of form
What is a gas?
a substance possessing perfect molecular mobility and the property of indefinite expansion, as opposed to a solid or liquid.
What is oxidation?
The combination of a substance with oxygen;
A reaction in which the atoms in an element lose electrons and the valence of the element is correspondingly increased
What is digestion?
The process by which food is converted into substances that can be absorbed and assimilated by the body. It is accomplished in the alimentary canal by the mechanical and enzymatic breakdown of foods into simpler chemical compounds
What is activation energy?
the minimum amount of energy required to convert a normal stable molecule into a reactive molecule
What is a physical change?
any process involving a substance's change from one state (gas, liquid, solid) to another without alteration of the chemical composition
What is a chemical change?
any change from one state (gas, liquid, solid) which is accompanied by alteration of the chemical composition; any process in which one or more substances are changed into one or more different substances
What are the phases of matter?
solid, liquid, gas, plasma
What are the states of matter?
solid, liquid, gas, plasma
Which stages in the rock cycle happen by physical changes?
Sedimentary rock (sedimentation, weathering); Metamorphic rock (without chemical change)
Which stages in the rock cycle happen by chemical changes?
Metamorphic rock & Igneous Rock
What is a proton?
Positive charged particle in nucleus of atom
What is a neutron?
Neutral charged particle in nucleus of atom
What is an electron?
Negative charged particle in electron cloud surround nucleus of atom
What is an anion?
A negative ion (gains electrons)
What is a cation?
A positive ion (gives electrons)
What are alpha particles?
a positively charged particle consisting of two protons and two neutrons, emitted in radioactive decay or nuclear fission; the nucleus of a helium atom
What is radioactivity?
the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element
What is condensation?
water vapor changes to liquid water
What is evaporation?
liquid water changes to water vapor
What steps of the water cycle are physical changes?
precipitation, condensation, evaporation
Can any steps of the water cycle be chemical changes? How?
What is atomic mass?
the number of protons + number of neutrons
What does the atomic number of an element represent?
the number of protons (in neutral atom can also be the number of electrons)
What are valence electrons?
The number of electrons involved in bonding; outer shell of electrons (between 1 and 8)
What is an energy level in an atom?
similar to a "shell"; holds specific number of electrons; determines many chemical and physical properties of element
What is the law of conservation of mass?
a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system
What is a coefficient?
number BEFORE the element or compound in a chemical formula; tells # of molecules
What is a subscript?
number AFTER an element, tells # of atoms of said element
What is a chemical formula?
a representation of a substance using symbols for its constituent elements; example, NaCl (sodium chloride)
What is a chemical equation?
a symbolic representation of a chemical reaction, specif. the reactants on the left and the products on the right, separated by an equal sign or directional arrows
What is a combustion reaction?
rapid oxidation accompanied by heat and, usually, light; example equation: CH4 + 2O2 -> CO2 + 2H2O
What is a synthesis reaction?
the forming or building of a more complex substance or compound from elements or simpler compounds; example equation: Na + Cl -> NaCl
What is a single-replacement reaction?
a single uncombined element replaces another in a compound. Two reactants yield two products; example equation: Zn + 2HCl -> ZnCl2 + H2
What is a double-replacement reaction?
parts of two compounds switch places to form two new compounds. Two reactants yield two products; example equation: AgNO3 + NaCl -> AgCl + NaNO3
What is a product?
the end result of a chemical reaction
What is a decomposition reaction?
a more complex substance breaks down into its more simple parts. One reactant yields 2 or more products. Opposite of synthesis reaction. Example equation: 2H2O -> 2H2 + O2
Which state or phase of water is more dense?
Which characteristic of water best explains its ability to dissolve a great variety of materials?
molecular arrangement (polar molecule)
What is a polar molecule?
A polar molecule has a partial positive charge in one part of the molecule and complementary negative charge in another part
Why does tap water conduct electricity but pure water (distilled) will not?
Tap water has dissolved ions which carry/conduct electricity
What is pH?
the symbol for the logarithm of the reciprocal of hydrogen ion concentration in gram atoms per liter, used to express the acidity or alkalinity of a solution on a scale of 0 to 14, where less than 7 represents acidity, 7 neutrality, and more than 7 alkalinity
What is an acid?
a compound usually having a sour taste and capable of neutralizing alkalis and reddening blue litmus paper, containing hydrogen that can be replaced by a metal or an electropositive group to form a salt, or containing an atom that can accept a pair of electrons from a base
What is a base?
a compound that reacts with an acid to form a salt, as ammonia, calcium hydroxide, or certain nitrogen-containing organic compounds; the hydroxide of a metal or of an electropositive element or group
What is litmus paper?
paper colored with litmus and used as an acid-base indicator; turns red with acid, blue with base (or no change)
What is an alkali?
a base
What is an electrolyte?
any substance that dissociates into ions when dissolved in a suitable medium or melted and thus forms a conductor of electricity
What is a reactant?
Element, elements, molecules, or compounds which combine together to make a product OR can be reduced to make multiple products
What is a solvent?
a substance that dissolves another to form a solution
Does solubility increase or decrease with increased temperature?
Usually increase, depends on chemical(s) involved
Does solubility increase or decrease with increased pressure?
A sample of an element has a volume of 78.0 mL and a density of 1.85 g/mL. What is the mass in grams of the sample?
144.3 g
A blck of maple wood with a volume of 405 cubic centimeters and a density of 0.67 g/cm3 is sawed in half. The density of the two smaller blocks is now ___.
the same as the original density
Which of the following groups contains members with similar chemical reactivity?

A. Li, Be, C
B. Be, Mg, Sr
C. Sc, Y, Zr
D. C, N, O
B. Be, Mg, Sr
Will elements in Group 16 of the periodic table gain or lose electrons when bonding?
Which group of elements on the periodic table are most resistant to forming compounds?
Group 18 or Noble Gases
Does density change with the state or phase of matter?
Yes, density changes because volume changes (mass should stay the same)

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