Glossary of Chemistry BIZNATCH

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anything that has mass and takes up space
law of the conservation of energy
energy cannot be created or destroyed, but can change form
law of the conservation of mass
matter cannot be created or destroyed in ordinary physical or chemical changes
How to convert from Celcius to Kelvin and vice versa
Celcius to Kelvin= +273.18

Kelvin to Celcius= -273.18
accuracy vs. precision
accuracy-a description of how close a measurement is to the true value of the quantity measured

presicion-the exactness of a measurement
an atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons
mass number
the sum of the numbers of protons and neutrons in the nucleus of an atom
atom number
the number of protons in the nucleus of an atom; the atomic number is the same for all atoms in an element
average atomic mass
the weighted average of the masses of all naturaly occuring isotopes of an element
Pauli Exclusion Principle
two particles of a certain class cannot be in exactly the same energy state
Hund's Rule
for an atom in the ground state, the number of unpaired electrons is the maximum possilbe, and these unpaired electrons have the same spin
Aufbau Principle
the structure of each successive element is obtained by adding one proton to the nucleus of the atom and one electron to the lowest enerby orbital that is available.
an atom, radical, or molecule that has gained or lost one electron and has a negative or positive charge
Covalent Bond
a bond formed when atoms share one or more pairs of electrons
the formula for an acid always begins....
with the letter H
Synthesis Reaction
a reaction in which two or more substances react to form a new compound

1 bonding electron, 3 lone pairs

2 bonding electrons, 0 lone pairs
2 bonding electrons, 2 lone pairs
3 bonding electrons, 1 lone pair
4 bonding electrons, 0 lone pairs
trigonal planar
3 bonding electrons, 0 lone pairs
combustion reaction
the oxidation reaction of an organic compound, in which heat is released

always uses hydrocarbon
decomposition reaction
a reaction in which a single compound breaks down to form two or more simpler substances

AB --> a+b
double displacement reaction
a reaction in which a compound forms from the apparent exchange of atoms or ions between two compounds

HCl + NaOH -->HOH + NaCl
single displacement reaction
a single element reacts with a compound and displaces another element from the compound

2Al + 3CuCl2 --> 2AlCl3 + 3Cu
molar mass
the mass in grams of 1 mol of a substance
in a chemical compound covalent bonds form when
pairs of electrons are shared between two nonmetal atoms
atoms of copper and iron tend to form
cations POSITIVE
and ion and its parent atom have the same
which of the following is not a property of an ionic compound

low boiling point
molten compound conducts electricity
compared with ionic compounds, molecular compounds...
have lower melting points
what is the metallic ion in the compound CuCl2
The chemical bond formed when two atoms share one or more pairs of electrons is a
covalent bond
a ciompound resulting from the formation of an ionic bond between a cation and an anion is...
an ionic ccompound
in naming a binary ionic compound the name of the ___ apears before the name of the___
metal, nonmetal
in a covalent bond, shared electrons move within a space called a ___ ___
molecular orbital
a molecule is a neutrally charged group of atoms held together by one or more _______ _______
covalent bonds
how is a covalent bond formed
when electrons are shared by 2 elements on the molecular orbital
for an electron in an atojm to change from the ground state to an excited state....
energy must be absorbed
elements in a group have similar
two which group of the periodic table to lithium and potassium belong
alkali metals
the elements in group 17 are known by what name
which is the best reason that the atomic radius generally increases in each group of elements?

-the nuclear charge increases
the number of neutrons -increases
-the number of energy levels increases
-a new octet
the number of energy levels increases
an electron that is found in the outermost energy level of an atom and determines an atoms chemical properties is called a
valence electron
planetary model
the statement that only two electrons may occupy an oribital is known as
pauli's exclusion principle
the statement that electrons fill up lower energy levels before occupying higher levels is known as the
Aufbau Principle
Why does a water molecule have a bent shape?
oxygen attracts the shared pairs more strongly than either hydrogen does, making the molecule polar and bent. Because it is bent, the polarities do not cancel out
properties of ionic compounds
-hi boiling/melting points
-good conductor as a liquid
-hard and brittle
matter includes all of the following except
water vapor
all of the following are examples of units except
in any chemical or physical process, energy is neither created nor destroyed
law of conservation of energy
a temp of 323 K = ___C
50 C
five darts strike at the center of the target. Whoever threew the darts is
both accurate and precise
**IN division and multiplication, the answer must not have more sig figs than the
number in the calculation wiht the fewest sig figs
energy is transferred from hot water to a cup. this energy is in the form of ____
heat energy
two types of matter that are pure substances are ____ and _____
elements and compounds
the capacity to do work or produce light is known as
a chemical reaction that releases energy is a ____ ____
exothermic reaction
the avg kinetic energy of the particles in a sample of matter is its
during the process of a phase change, heat is being added to the substance, but the temp remains constant. using what you know about the law of conservation of energy, explain why the temp is constant during a phase change
during a phase change, (ice melting)i the energy from ehat is being used to make this change by breaking up particfles not warming the substanced. Energy is never created nor destroyed, so in this case all the energy must be used to complete the process of ice --> H2O
explain diference between hetero and homogenous mixture. give ex
a homogeneous mixture is a mixture in which all the properties of the substance are spread equally throughout the mixture. (sweetened tea)

a heterogeounous mixture is a mixture in which the propterties of a substance are not spread evenly throughout the mixture (chocolate chip cookies)
isotopes of an element contain different numbers of
what did rutherford conclude about the structure of the atom?
an atom contains a small, dense, positivelyt charged region
most of the volume of the atom is occupied by the
electron cloud
the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes is known as the law of
conservation of mass
according to Dalton's atomic theory, atoms of each element are
identical in size, mass, and other properties
atoms become charged by
losing electrons
an aluminum isotope consists of 13 protons 13 electrons 14 neutrons. mass number=?
the number of protons in the nucleus of an atom is called the
atomic number
the mass in grams of 1 mol of a substance is its
molar mass
coined term "atom"
why do chemists work with moles instead of individual atoms?
moles are used as coundintg units. they make conversions from grams --> atoms easier
how did scientists know that atoms must contain neutrons?
because the mass of the electrons protons and nucleus did not equal the total mass of the atom, hence the neutron
isotopes of an element have different
atomic masses
atoms of the same element must contain the same number of

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