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Chemistry Test Review
Terms in this set (72)
basic particle of matter made of protons, neutrons, and electrons
What are the three parts of an atom?
Protons (positive), Neutrons (neutral) and Electrons (negative)
What is the structure of an atom?
protons are in the center of the nucleus glued to neutrons
electrons flying around the outside
What is determined by the structure of an atom?
which element it is
a pure substance consisting of only one type of atom
What is compound?
2 or more elements chemically combined
either an element or compound
What's the purpose of the Periodic Table?
to organize the elements
allows prediction of chemical & physical properties
What is the difference between Groups and Periods?
groups are called families and are vertical columns
periods are horizontal rows
protons and electrons in each atom
number of protons and neutrons in each
How do you find atomic number?
protons + electrons
How do you find the number of neutrons?
atomic mass - atomic number
What is a chemical reaction?
creation of a new substance-happens when atoms are not happy with # of valence electrons
What subatomic particle is being traded or shared during chemical reactions?
What is the Conservation of Mass law?
mass reactants = mass products
Matter (atoms) are never created or destroyed. All atoms in = all atoms out
What is a chemical formula?
shorthand way of representing molecules
What is a chemical symbol?
shorthand way of writing elements
What is a chemical equation?
shorthand way of representing a reaction
What are reactants?
"ingredients" of reactions
What are products?
new substances made
What is an exothermic reaction?
gives off heat
What is an endothermic reaction?
absorbs heat/gets cold
What are some examples of exothermic reactions?
fire, digestion, instant handwarmers
What are some examples of endothermic reactions?
baking cookies, instant cold pack
What is electrolysis?
breaking up molecules with electricity
What is the difference between electrolysis and synthesis?
Synthesis combines and electrolysis breaks down
What are 4 ways to speed up the rate of chemical reaction?
use a catalyst
increase surface area
Name the properties of metal.
good conductors of heat & electricity
tend to give away electrons
Name the properties of nonmetals.
gases at room temp
tend to gain electrons
What are Noble Gases?
group 18 of periodic table-very nonreactive-last column of Periodic Table
can be hammered into foil/bendable
eager to share & trade
easily drawn into wire when pulled
What are chemical bonds?
sharing or trading of electrons by atoms
only observed during chemical reactions
observed any time
What state of matter are most elements at room temperature?
Where and how are elements made?
in stars & supernovas by fusing various protons together
involves actual numbers
only letters & words (like color, shape, texture)
What is matter?
anything that has mass & takes up space
What are 6 indications that a chemical reaction has taken place?
hard/impossible to reverse
no change in composition
new substances made
nucleus of atom changes
Why do chemical reactions take place?
atoms aren't "happy" with the number of outermost (valence) electrons they have
Which electrons are available for chemical bonding and why do they bond?
outermost (valence) electrons
What are the parts of the Fire Triangle?
fuel, oxygen, heat
How does knowledge of the Fire Triangle allow us to control combustion reactions?
if any part of the triangel is missing or weak, the fire goes out
Why does a match held upright burn so differently than a match held upside down?
hot air rises since it's less dense so the heat energy reaches the fuel better when the match is upside down
How do you read chemical reactions?
from left to right
What does an arrow in a chemical reaction represent?
produces or yields
pH less than 7
same as basic pH above 7
pH exactly 7
What is the pH scale, and how does it determine acidity or alkalinity?
pH scales go 0-14 with
7.1-14 alkaline (basic)
Sour taste, pH less than 7, react with metals, conduct electricty
bitter & slippery, pH >7, conduct electricity
can be corrosive
How does chemical neutralization occur?
whenever an acid and base combine
What is always one product of neutralization?
Why should we be more concerned about acid rain in the Adirondack region, but not in the Rochester region?
Adirondacks don't have limestone/carbonate-based soils to neutralize the acidic rain. Acids can build up and kill wildlife
What substances are found in the Periodic Table?
electrons actually go from one atom to another-stronger
electrons are shared between atoms-medium strength
Why are melting and dissolving chemical changes?
they are easily reversed-no new substance is created
How are melting and dissolving similar?
both are physical changes
How are melting and dissolving different?
Melting-heat is required, phase change
dissolving-heat is not required, not a phase change
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