Chemical reactions
a substance or molecule that participates in a
chemical reaction
reactant
— a combination of chemical symbols
and numbers to represent a substance
Chemical formula
the transfer of energy
from particle to particle as they
bump into each other.
conduction
When you touch a warm
object ___________________ is
transferred from the object
to your hand.
thermal energy
states that matter
cannot be created or destroyed in ordinary chemical or
physical changes.
Law of conservation of matter/mass
— a substance that forms in a chemical reaction
product
— a representation/model of a chemical
reaction that uses symbols to show the relationship
between the reactants and the products
chemical equation
The measurement of the average motion of the particles in a substance.
temperature
Most chemical processes involve a
change in_________________
energy
the transfer of energy through space by
electromagnetic waves
radiation
the process by which one or more
substances change to produce one or more different
substances
Chemical reaction
a number below and to the
right of the symbol, shows how many
atoms of that element there are.
subscript
The total kinetic energy of a substance's particles
thermal energy
Some processes, such as melting ice
cubes, ________________ thermal energy.
Other processes, like the burning of paper, ________ thermal energy.
absorb; release
During a chemical reaction, the same atoms that make
up the original substance or substances...
regroup into
different particles to form new substances.
Physical properties of substances include:
give 4
density, melting point,
boiling point, color, texture, odor, solubility, malleability,
and conductivity.
a number placed in front of a chemical formula to show how many molecules of the substance are represented in the chemical equation.
coefficient
The transfer of energy by moving liquids or gasses through circulation of the particles is called
convection
If a large amount of a solid melts, the amount of thermal energy absorbed will be ______________ than if a small amount of the solid melts.
larger
To determine whether a chemical
reaction has taken place, you can
test the properties of the
substances before and after
the change.
Why?
Signs a chemical reaction may have taken place:
at least 4
Change in temperature; change in color; change in taste; release of odor; formation of a gas (bubbles/fizzing); formation of a precipitate
Describe what is happening in WORDS:
Zn + 2HCL → ZnCl2 + H2
.
one atom of zinc reacts
with two molecules of hydrochloric acid
to make on unit of zinc chloride and
one molecule of hydrogen gas.
.
the transfer of thermal energy from one object to another or one region to another.
heat
Name and explain the 4 factors that affect reaction rates.
• Concentration: The more reactants that are available, the
faster they can react.
• Temperature: If the particles are moving faster they are
more likely to collide and react.
• Catalysts: Can make a reaction more likely to occur.
• Surface area: Salt will dissolve faster if it is ground up.
More surface area allows more water molecules to touch the
salt particles.
A reaction can be modeled by these reactants and products:
Pb(NO3)2+ NaI →PbI2+ NaNO3
Is this equation balanced?
No.
This is the balanced equation
Pb(NO3)2+ 2NaI →PbI2+ 2NaNO3