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science mid term

Terms

undefined, object
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ground state
when all the electrons in an atom have the lowest possible energies
mass
the amount of matter in an object; a measurement of the inertia of an object, which depends on the amount of matter the object contains
covalent bonds
a chemical bond in which two atoms share a pair of valence electrons
boron family
the column with boron at the top
Plasma
a state of matter in which atoms have been stripped of their electrons
compound
a substance that is made from two or more simpler substances and can be broken down into those simpler substance
avogadros number
6.02x10^23
colloid
a mixture that contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspensio
solvent
the substance in which a the solute dissolves
oxidation
any process in which an element loses electrons during a chemical reaction
Vapor pressure
the pressure caused by the collisions of particles in a vapor with the walls of a container
polyatomic ion
a covalently bonded group of atoms that has a positive or negative charge and acts as a unit
Isotopes
atoms of the dame element that have different numbers of neutrons and different mass numbers
chemical energy
the energy stored in the chemical bonds of a substance
Physical property
any characteristic of a material that can be observed or measured without changing the composition of the substances in the material
element
a substance that cannot be broken down into simpler substances
Thomson
the first evidence that atoms are made of even smaller particles
Exothermic
a description of a change in which a system releases energy to its surroundings
electron dot diagram
a model of an atom in which each dot represents a valence electron
heterogeneous mixture
a type of mixture in which the parts of the mixture are noticeably different from one another
Democritus
believed that all matter consisted of extremely small particles that could not be divided; he called these particles atoms
valence electrons
outer electrons
reactant
the substance that undergoes change
reduction
the process in which an element gains electrons during a chemical reaction
ionic bond
the force that holds cations and anions together
controlled variable
the factor in your experiment that doesn't change
crystal
solid whose particles are arranged in a lattice structure
Kinetic energy
the energy an object has due to its motion
Boiling point
the temperature at which a substance boils; the temperature at which vapor pressure is equal to atmospheric pressure
percent error
the difference of your answer and the actual answer over the actual answer
alkaline earth
elements in the column to the right of the furthest left
nonmetals
elements that are poor conductors of heat and electric current
ionization energy
the process by which neutral molecules gain or loose electrons
Phase change
a reversible physical change that occurs when a substance changes from one state of matter to another
combustion
one in which a substance reacts rapidly with oxygen, often producing heat and light
Pressure
the result of a force distributed over an area
manipulated variable
variable that undergoes change during an experiment
controlled experiment
certain you will have a controlled factor to compare your results with
Gas
the state of matter in which a material has neither a definite shape nor a definite volume
Vaporization
the phase change in which a substance changes from a liquid into a gas
Endothermic
a description of a change in which a system absorbs energy from it surroundings
period
each row in the periodic table
Sublimation
the phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first
Nucleus
the dense, positively charged mass located in the center of an atom
polar covalent bond
a covalent bond in which electrons are not shared equally
Filtration
a process that separates materials based on the size of their particles
precision
limited by markings on a tool; a gauge of how exact a measurement is
scientific method
a method of research in which a problem is identified, relevant data are gathered, a hypothesis is formulated from these data, and the hypothesis is empirically tested.
chemical formula
a notation that shows what elements a compound contains and the ratio of atoms or ions of these elements in the compound
mol
a amount of a substance that contains approximately 6.02x10^23 particles of the substnace
forming bonds
releases energy, exothermic
density
the ratio of a material's mass to its volume
anion
an ion with a negative charge
conservation of mass
states that mass is neither created nor destroyed in chemical reaction
Physical change
a change that occurs when some properties of a material change, but the substances in the material stay the same
electron configuration
the arrangement of electrons in the orbitals of an atom
atomic mass unit
one twelfth the mass of a carbon 12 atom
Melting point
the temperature at which a substance changes from solid to liquid
Dalton
theory that all matter is made up of individual particles called atom; all elements are composed of atoms, all atoms of the same element have the same mass and atoms of different elements have different masses, compounds contain atoms of more than one element, and atoms of different elements always combine in the same way
Electrolysis
separating water using electricity
Reactivity
the property that describes how readily a substance combines chemically with other substances
basic branches of science
bio, chem, physics, geology
pure substance
matter that always has exactly the same composition; an element or compound
hypothesis
stating what you think will happen
coefficient
number that appear before a formula in a chemical equation to show the relative proportion of each reactant and product
alloy
a mixture of two or more elements, at least one of which is a metal
Electron
a negatively charged subatomic particle that is found in the space outside the nucleus of an atom
sloute
a substance whose particles are dissolved in a solution
chemical equation
a representation of a chemical reaction in which the reactants and products are expressed as formulas
metals
elements that are good conductors of electric currents and heat
Condensation
the phase change in which a substance changes from a gas or vapor to a liquid
suspension
a heterogeneous mixture that separates into layers over time
molar mass
the mass of one mol of a substance
cation
an ion with a positive charge
single replacement
a reaction in which one element takes the place of another element in a compound
length
the straight line distance between two points
molecule
a neutral group of atoms that are joined together by one or more covalent bonds
synthesis
a reaction in which two or more substances react to form a single substance
atomic mass
the sum of the protons and neutrons
molecule
a neutral group of atoms that are joined together by one or more covalent bonds
energy level
the possible energy that an electron in an atom can have
carbon family
the column with carbon at the top
responding variable
the variable that results from the experiment
double replacement
one in which two different compounds exchange positive ions and form two new compounds
inert
not moving
noble gases
the elements in the column furthest right
equilibrium
a state in which the forward and reverse paths change take place at the same rate
Malleability
the ability of a solid to be hammered without shattering
nitrogen family
the column with nitrogen at the top
metallic bond
the attraction between a metal cation and the shared electrons that surround it
theory
a statement that cannot be proven wrong
volume
the amount of space taken up by an object
Deposition
the phase change in which a gas or vapor changes directly into a solid without first changing into a liquid
periodic table
an arrangement of elements in columns, based on a set of properties that repeat row to row
accuracy
the closeness of a measurement to the true value of what is measured
Bohr
discovered that electrons move from energy level to energy level
Neutron
a neutral subatomic particle that is found in the nucleus of an atom
Distillation
a process that separates the substance in a solution based on their boiling point
Proton
a positively charged subatomic particle that is found in the nucleus of an atom
atom
the smallest particle of an element
Atomic number
the number of protons an element has
Absolute zero
a temperature of 0 kelvins
decomposition
a reaction in which a compound breaks down into two or more simpler substnaces
Flammability
a material's ability to burn in the presence of oxygen
Conductivity
a material's ability to allow heat or electric charges to flow
Liquid
the state of matter in which a material has a definite volume but not a definite shape
product
the new substance formed as a result of a change
halogens
elements in the column left of the furthest right
orbital
a region of space around the nucleus where an electron is likely to be found
Temperature
a measure of how hot or cold an object is compared to a reference point
oxygen family
the column with oxygen at the top
law
a theory about which we can be most certain
Chemical change
change that occurs when a substance reacts and forms one or more new substances
Rutherford
the theory that said that there was a nucleus
scientific notation
a way of expressing a value as the product of a number between 1 and 10 and a power of ten
solution
a mixture that forms when substances dissolve and form a homogenous mixture
significant figures
all the digits in a measurement that are directly measured, plus the last digit, which is estimated
homogenous mixture
a type of mixture in which the substances ate so evenly distributed that it is difficult to distinguish one substance in the mixture from another
family
each column on the periodic table
Precipitate
a solid that forms a separates from a liquid mixture
Viscosity
the tendency of a liquid to keep from flowing; resistance to flowing
temperature
a measure of how hot or cold an object is compared to a reference point
Alkali metals
elements in the far left column
electron cloud
a visual model of the most likely locations for electrons in an atom
metalloids
elements with properties that fall between both those of metals and nonmetals
nonpolar
equal pulling; positive, negative; battery
Solid
the state of matter in which materials have a definite shape and a definite volume
Density
the ratio of a material's mass to its volume
Evaporation
the process that changes substance from a liquid to a gas at temperatures below the substance's boiling point
breaking bonds
requires energy, endothermic

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