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Science unit 5
Study guide q&a
35
Science
8th Grade
10/25/2011

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Term
who was Dimitri Mendeleev?what did he create?
Definition
he was a russian chemist and a chemistry teacher: he created the periodic table.
Term
how did he arrange his creation?
Definition
by increasing atomic mass in the same column.
Term
where so a set properties repeat on the periodic table?
Definition
row to row
Term
what value increases exactly by one from left to right across a row of the periodic table?
Definition
the atomic number
Term
how is the arrangement of the modern periodic table that same as Mendeleev's?
Definition
by increasing mass
Term
each row in the periodic table is called a _______.
Definition
period
Term
each column in the periodic table is called a __________.
Definition
group
Term
what known as the pattern of repeating properties of elements
Definition
periodic law
Term
how is the atomic mass of an element determined?
Definition
weighted average of the masses of the masses of the elements isotopes.
Term
what is used to define an atomic mass unit? what is the abbreviation?
Definition
1/12th carbon atom: atom
Term
how is an elements isotope used to find the atomic mass?
Definition
wighted average of the masses of the elements isotopes.
Term
what are the 3 classes of elements?
Definition
metals nonmetals and metalloids.
Term
give two characteristics of a metal.
Definition
not brittle, conductivity, solid at room temp.
Term
describe two characteristics of a nonmetal.
Definition
brittle, low boiling point, poor conductivity.
Term
what happens o nonmetals at room temp?
Definition
they turn to gases and brittle.
Term
what is the most nonreactive nonmetal
Definition
flourine
Term
what are metalloids?
Definition
elements with properties that fall between those of metals and nonmetals.
Term
across a period from left to right, how do the elements change?
Definition
become less metallic to more non metallic
Term
what is a valence electron?
Definition
e- that is in the highest occupied energy level of an atom
Term
elements in the same group have_______properties.
why?
Definition
similar
because they have the same number of valence electrons.
Term
what are the elements in group 1a called?
Definition
alkali metals
Term
how many valence electrons have to be extremely reactive?
Definition
1 or 7
Term
to keep the valence electrons from reacting, what are they stored in?
Definition
under oil or under argon
Term
where are the alkaline earth metals located?
Definition
group 2a
Term
what are these medals used for?
Definition
photosynthesis, chalk and coral
Term
group 3a contains the _____ family
Definition
boron
Term
what is the most abundant METAL in earths crust?
Definition
aluminum
Term
in group 4a of the carbon family , what do most of the most compounds in your body contain?
Definition
carbon
Term
most fertalizers contain what elements from group 5a...
Definition
nitrogen and phosphorus
Term
___________is the most abundant ELEMENT in earths crust. the element that is found in nature only in compounds is SODIUM
Definition
oxygen
Term
how are halogens similar?
Definition
have the same chemical properties
Term
the most reactive NONMETAL is also the halogen ______ in group 7a
Definition
flourine
Term
which column contains the most reactive metals?
Definition
the far left
Term
elements in group 8an are called the _____ ______
Definition
noble gasses
Term
list 3 characteristics of the noble gases. what can they be used for?
Definition
colorless, odorless, and extremely unreactive
they can be used for neon lights
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