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83 Cards in this Set

  • Front
  • Back
the basic unit of matter is called an
atom
describe the nucleus of an atom
protons and neutrons are located in the nucleus and are binded by a strong force
protons have a _______ charge and are located in the ________.
positive;nucleus
neutrons have a _________ charge and are located in the _________.
neutral;nucleus
electrons have a __________ charge and are ___________ the nucleus.
negative;surround
why are atoms neutral despite having charged particles?
because atoms have equal numbers of electrons nad protons and because these subatomic particles have = but opposite charges, the atoms are neutral.
chemical element
pure substance that consists entirely of one type of atom.
what does an element's atomic number represent?
the number of protons in an atom of an element
isotopes
atoms of the same element that differ in the number of neutrons they contain.
isotopes are identified by
their mass number
why do all isotopes of an element have the same chemical properties?
they have the same number of electrons
chemical compound
substance formed by the chemical combo of 2 or more elements in definite properties.
what holds atoms in compounds together?
chemical bonds
covalent bond
electrons are shared between atoms
ionic bond
one or more electrons are transferred from one atom to another
ion
positively charged and negatively charged atom
an atom that loses electrons has a ________ charge.
positive
an atom that gains electrons has a ______ charge.
negative
the structure that results when atoms are joined by covalent bonds are called _______.
molecule
the slight attractions that develop between oppositely charged regins of nearby molecules are called _____________.
van der waals force
in a water molecule each hydrogen forms a _______ covalent bond.
single
atoms can share 6 electrons and form a _______ bond.
triple
matter has _______ and ________.
mass and volume
matter can be _________, ____________, or _________.
pure substances, chemical compounds, mixtures
matter may exist in three different states:
solid, liquid, gas
matter may also be ______________ or ____________ mixtures
homogenous, heterogeneous
are all matters visible? explain.
no, some may be odeorless and colorless gases
does matter take up space?
yes all matter has mass and volume
what is matter made of?
elemental atoms and chemical compounds
atom
an entity which cannot be divided furthur and still maintain its unique property
atoms are made up of _____________ particles.
subatomic
how are protons and neutrons bound to the nucleus?
by a strong force
some isotopes are __________ and _________.
unstable, radioactive
element
substance consisting entirely of one type of atom
what does it mean when an isotope is radioactive?
their nuclei are unstable and break down at a constant rate over time
are radioactive isotopes dangerous?
yes it can be dangerous but radioactive isotopes have a number of important scientific and practical uses
radioactive isotopes can be used to
treat cancer, to kill bacteria that causes food to spoil, and can be used as labels or “tracers” to follow the movements of substances within organisms
Because isotopes the same number of electrons..
all isotopes of an element have the same chemical properties.
a chemical formula indicates the composition of a(an)
compound
when atoms share four electrons, it forms a _______ bond.
double
Some atoms have a _______ attraction for electrons than do other atoms.
stronger
when a covalent bond begins to share electrons, the sharing is _______ equal.
not always
Even when the sharing of a covalent bond is equal, the rapid movement of electrons can create _______ on a molecule that have a tiny positive or negative charge.
regions
van der waals force
a slight attraction that develops between the oppositely charged regions of nearby molecules
a water molecule is _________.
neutral
what results from the oxygen atom being at one end of a water molecule and the hydrogen atoms being at the other end?
oxygen end: slight negative charge
hydrogen end: slight positive charge
why is a water molecule polar?
because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.
_________ bonds are the strongest bonds that form between molecules.
hydrogen
cohesion attraction
an attraction between molecules of the same substance
adhesion
an attraction between molecules of different substances
why is water extremely cohesive
because of hydrogen bonding
the rise of water in a narrow tube against the force is called
a capillary action
how does capillary action affect plants?
because it draws water out of the root of the plants and up into its stems and leaves
what is a mixture?
material composed of 2 or more elements or compounds that are physically mixed together but not chemically combined
a mixture of two or more substances in which the molecules of the substances are evenly mixed is called a
solution
the greatest solvent in the world is
water
what is a suspension?
mixture of water and nondissolved materials
solute and example
substance that is dissolved in solvent to make a solution; tablesalt
solvent and example
substance in which solute dissolves; water
two water molecules react to form
ions
why is water neutral despite the production of hydrogen ions and hydroxide ions?
because the number of positive hydrogen ions produced is equal to the number of negative hydroxide ions produced.
what does the pH scale indicate?
if something is acidic, basic or neutral
what number is neutral on the pH scale?
7 (water)
the more protons an atom has, the ________ the attraction is for electrons.
stronger
there is a greater probability of finding shared electrons near an atom with a ________ amount of protons an atom as
greater
Because of their partial positive and negative charges..
polar molecules such as water can attract each other
Hydrogen bonds are ______ strong as covalent or ionic bonds
not as
Water's cohesion causes molecules on the surface of water to be drawn _______, which is why drops of water form beads on a _______ surface
inward;smooth
Adhesion between water and glass also causes water to rise in a narrow tube against the force of gravity. what is this effect called?
a capillary action.
Cohesion and adhesion are similar in that
both are attractions between molecules.
all components of a ________, are evenly distributed.
solution
Water's ________ gives it the ability to dissolve both ionic compounds and other polar molecule
polarity
When an ionic compound such as sodium chloride is placed in water, water molecules _______ and ________ the positive and negative ions.
surround, separate
Some materials do not dissolve when placed in water but separate into pieces so small that they do not settle out. This is called ___________. give an example
suspensions; blood
the higher the pH the more ________ the solution
basic
the lower the pH the more _______ the solution
acidic
base
is a compound that produces hydroxide ions (OH− ions) in solution
acid
is any compound that forms H+ ions in solution.
buffers
are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH
Controlling pH is important for maintaining __________.
homeostasis
A molecule in which the charges are unevenly distributed is called a
polar molecule
A dissolved substance is called a
solute
A compound that produces hydroxide ions in solution is called a
a base