Unit 2 Test Flashcards
What are atoms made up of?
Subatomic particles
What are the three types of subatomic particles?
protons, neutrons, electrons
Where is the nucleus and what is it made up of?
Its in the center of an atom and made up of protons and neutrons, tightly packed together
Where is the electron cloud?
On the outside of the nucleus
What is the atomic number?
The same as the number of protons
What do all atoms of the same element have in common?
They all have the same number of protons
What is a proton’s charge and relative mass?
Positive and one
What is the number of electrons in a neutral atom?
the number of protons
What is a electron’s charge and relative mass?
negative and zero
What is a neutron’s charge and relative mass?
No charge and one
What do subscripts (in a chemical formula) represent?
The relative number of each type of atom
Does a subscript come in before or after the element symbol?
After
When are parenthesis used?
When a subscript effects a group of atoms
Describe a solid (in terms of kinetic theory)
- fixed shape
- particles closely packed together
- particles held in one position and vibrate around
Describe a liquid (in terms of kinetic theory)
- particles stay relatively close together
- particles can move around each other
Describe a gas (in terms of kinetic theory)
- particles are far apart
- particles move rapidly and collide with each other and with the walls of the container
What is the mass # (number)?
The sum of protons and neutrons in an atom
What are isotopes?
atoms of the same element that have a different number of neutrons (sometimes isotopes are radioactive)
What is atomic mass?
The weighted average of the masses of all the known isotopes of the element
What is molar mass?
The mass of one mole of any element in grams (the same as atomic mass but with a unit)
What is the only way to form a compound from elements?
A chemical reaction
Does bond breaking require or release energy?
requires energy
Does bond making require or release energy?
releases energy
What is a solution?
a homogeneous mixture made up of very tiny particles (molecules, atoms, ions)
What is the solvent?
the substance that makes up the largest % of the solution
What is the most common/universal solvent?
water
What is the solute?
The substance being dissolved (in water, solutes are polar covalent comps. or ionic comps.)
What is a saturated solution?
a solution that has all the dissolved solute that it can hold (max solute)
How can you identify that a solution is saturated?
Adding more solute will result with undissolved solute particles at the bottom after mixing
What is an unsaturated solution?
A solution that can still hold more solute
What is filtrate?
The liquid that passes through the filter
What do you measure volume with?
graduated cylinder
What do you measure mass (g) with?
electronic balance
What do nuclear reactions change?
Nuclear reactions change the composition of an atom’s nucleus
What do chemical reactions change?
Only the outer electrons (nucleus stays the same)
What does the stability of a nucleus depend on?
The ratio of protons to neutrons
What are radioisotopes?
radioactive isotopes that have unstable nuclei
What is Carbon-14
A radioisotope of carbon
What is radioactive decay?
when an unstable nucleus loses energy by spontaneously emitting radiation
Why is radiation called decay?
the original nucleus decomposes and forms a new nucleus (all while releasing radiation)
What are the three kind of radiation?
Alpha, beta, gamma
What is an alpha radiation?
- consist of 2 neutrons and 2 protons
- identical to helium-4
- do not have much penetrating power
What is beta radiation?
- when a neutron changes into a proton and electron (electron gets shot out of nucleus)
- 100 times more penetrating then alpha particles
What is gamma radiation?
- very energetic form of light (human eyes cannot see)
- accompanies alpha and beta radiation
- much more penetrating (only stopped by heavy shielding)
What is the symbol for gamma radiation?
Y
What is the unit for atomic mass?
amu
What are the indicators of a chemical reaction?
- emission of light or heat
- formation of gas
- formation of a precipitate (when a solid forms)
- color change
- emission of odor
What are the 2 parts of a chemical reaction?
- Reactants (substances you start with)
- Products (substances you end with)
What is a catalyst?
A substance that speeds up a reaction without being changed by the reaction
What’s a biological/protein catalyst?
Enzymes
What are exothermic reactions?
- release energy (as heat)
- bonds formed
making substance cooler with potential energy
What are endothermic reactions?
- absorbs heat
- bonds broken
making substance warmer with kinetic energy
What are the 5 types of chemical reactions?
synthesis, decomposition, single replacement, double replacement, combustion
What are synthesis reactions?
- also known as combination reactions
- two elements or compounds are combined to make one compound (release energy - exothermic)
A+B ➝AB
What are decomposition reactions?
- breakdown of compounds into smaller compounds or element (uses energy - endothermic)
AB ➝A+B
What is single replacement?
- also known as single displacement
- one element replaces another (reactants an element and a compound, products dif. element and compound)
A+BC ➝AC+B
What is double replacement?
- two compounds replace each other (reactants iconic compounds or acid)
- usually in aqueous (aq) solution
AB+CD ➝AD+BC
What is combustion?
A reaction where compound reacts with oxygen (products always are C0₂ + H₂O)
What are the steps of recognizing the type of chemical equation?
What is matter?
anything that takes up space
What are the two types of matter?
pure substances and mixtures
What are the two types of pure substances?
compound (molecule) and element
What are the two types of mixtures?
Heterogeneous and Homogeneous (solution)
What are the two types of heterogeneous mixtures?
suspensions and colloids
Are solutions clear?
yes (a beam of light passing through them cannot be seen)
What does aqueous (aq) mean?
dissolved in water
What does solubility mean?
the measure of the amount of solute that can dissolve in a specific amount of solvent at a specific temperature and pressure
What is a solubility curve?
A curve that displays how much solute will dissolve in a given amount of solvent at a specific temperature
what is the solution equilibrium?
When the rate of undissolved solute coming in equals the rate of undissolved solute going out
What is a supersaturated solution?
when a solution contains greater than the max solute
How do you find how many significant figures there are?
When decimal point is present, count sig. digits starting with the first non-zero digit on the left.
When decimal point is absent, count sig. digits starting with the first non-zero on the right.
(present-left, absent-right)
What do you do when multiplying or dividing?
Round the answer to the least number of significant digits
What do you do when adding or subtracting?
Round the answer to the least number of decimal places
What is a counting?
A number with an exact value
What are quantities?
defined numbers like those in a measurement system
What is an estimated digit?
the last digit taken using a measurement device
How do we balance chemical equations?
we adjust the coefficients until the equation is balanced
*balance compounds before other elements and balance O and H last.
What does a triangle over the yield sign mean?
Heat
What does cat over the yield sign mean?
Catalyst
Are nuclear reactions affected by changes in temperature, pressure, or catalysts?
No
Can nuclear reactions be sped up, slowed down, or shut off?
No
What is radiation?
The penetrating rays and particles emitted by a radioactive source.
What two things does atomic mass represent?
- The average mass of a single element in amu
- the mass of one mole of atoms in grams
What is kinetic energy?
energy of movement (attractions between molecules, determines how freely they can move and whether they take the shape of a container or not)
Do liquids have fixed volume?
Yes
Do gasses have fixed volumes?
No
What is electrolysis?
Process where electrical energy is used to produce a chemical change
What is oxidation?
reduction caused by electrolysis oxidation taken away or added by electrical current
Who was John Dalton and what did he concur?
the father of modern chemistry
- believed that elements are composed of tiny particles called atoms and all atoms of one element are the same
What do protons define?
an elements identity
What do electrons (ions) define?
an elements chemical properties
Who discovered electrons?
TJ Thompson in 1897
What does MG stand for?
Magnesium
What does Li stand for?
Lithium
What does Ba stand for?
Barium
What does Ag stand for?
Silver
What does Na stand for?
Sodium
What does Au stand for?
Gold
What does Cu stand for?
Copper
What does F stand for?
Fluorine
What does As?
Arsenic
