Chemistry Final Review

Question 1

What are the six steps of the scientific method?

Answer 1

Question, Background research, hypothesis, Test/Experiment, Analyze data and conclude, communicate results

Question 2

In an experiment what is the independent variable?

Answer 2

Variable that stands alone and isn’t changed by other variables you are trying to measure.

Question 3

What is a dependent variable?

Answer 3

What you measure in an experiment what is affected

Question 4

What is the control variables?

Answer 4

Held constant variable, kept the same

Question 5

Why do scientists only vary one variable in an experiment?

Answer 5

Ensures that the experimental outcomes is clearly due to one identifiable factor.

Question 6

You want to test whether playing music in front of plants will affect their overall growth. You play constant music in front of plant 1 for a month and no music in front of plant b for a month. What would be a hypothesis for the experiment?
What is the independent, dependent, and control variables?
If at the end of a month both plants are the same height. What would be a conclusion for the experiment?

Answer 6

Hypothesis: If I play music in front of plants they will grow.

Independent: Music being played in front of plants

Dependent: growth of plants

Control: Type of plant/ light exposure

Conclusion: Playing music in front of these plants significantly causes growth

Question 7

What is the measurement system all scientists use and why? What are examples of these?

Answer 7

SI Units because it’s easier to compare and set up on a loose 10.
Examples: Length - meter (m)
Time - second (s)
Amount of substance - mole (mol)
Temperature - kelvin (K)
Luminous intensity - candela (cd)
Mass - kilogram (kg)

Question 8

What is the definition for accuracy and precision? What would be an example for each?

Answer 8

Accuracy: how close to a desired valve you are
Ex: if a micrometer is used to measure a 15 mm standard gauge block, and it produces a 15 mm reading, it is considered accurate
Precision: how close the results are
Ex:if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise.

Question 9

How many sig figs are within 0.002030?

Answer 9

4

Question 10

Round 306732 to 3 sig figs?

Answer 10

30700

Question 11

What is 3.04x10^-4?

Answer 11

30400.0

Question 12

What is 2690000?

Answer 12

2.69x10^-6

Question 13

Give the answer in the correct number of sig figs?

Answer 13

1824> round to 1800

Question 14

What is the definition of an element?

Answer 14

Cannot be simplified into any other substance

Question 15

What is a compound?

Answer 15

Two or more atoms chemically bonded it definite proportions. Ex: H20, Nacl

Question 16

What is a mixture?

Answer 16

Combo of 2 or more substances where substances maintain their properties

Question 17

What are the four states of matter and describe each according to the space between particles and particle movement?

Answer 17

Solid, Gas, Liquid, Plasma

Question 18

What is a solid?

Answer 18

Has definite volume and definite shape
Inter-molecular forces are strong.

Question 19

What is a gas?

Answer 19

No definite volume and shape- weak inter-molecular forces

Question 20

What is a liquid?

Answer 20

definite volume but no definite shape

Question 21

What is a plasma?

Answer 21

Happens at high temps- has free floating electrons and nuclei allowing electricity to follow ex: lightning

Question 22

What is the kinetic molecular theory? How are the particles of a liquid affected when it absorbs energy? When it release energy?

Answer 22

Explains states of matter, and is based on the idea that matter is composed of tiny particles that are always in motion. Liquid when energy is absorbed goes to a gas. When it releases it goes to a solid.

Question 23

What phase change occurs to a liquid substance if energy is absorbed? What phase change occurs to a liquid substance if energy is released?

Answer 23

Gas

Solid

Question 24

What is happening to kinetic energy of the water during each phase of the graph and what is happening to the state of matter during each portion of the graph?

Answer 24

If energy is continually added that energy allows molecules to move faster or allow a change in state. Either releases energy or absorbs.

Question 25

When does an object sink or float in water?

Answer 25

Sink if more dense than water
Float if less dense than water

Question 26

How much mass does a 30cm3 piece of iron weigh? Density of Iron= 7.86g/cm3?

Answer 26

235.8

Question 27

What is the equation for density?

Answer 27

d=m/v

Question 28

What happens to the density of a liquid if enough energy is added? (what state would it become)?

Answer 28

Temp increases, molecules move faster and spread apart. decreases liquids density. Will become a gas.

Question 29

How are specific wavelengths of light emitted from an atom?

Answer 29

Part of an atom. Atom has a negatively charged part called electron.

Question 30

What is a proton and where is it located?

Answer 30

Positively charged particles and found in nucleus.

Question 31

What is a neutron and where is it located?

Answer 31

Neutral particles and located in nucleus

Question 32

What is a electron and where is it located?

Answer 32

Negatively charged and orbiting nucleus.

Question 33

What is the atomic number and mass number of an atom? How do you identify the atomic number and mass number of an atom?

Answer 33

Atomic #= # of protons
Mass #= Total # of protons and neutrons in nucleus

Question 34

What is a atom, ion, and Isotope?

Answer 34

Atom: smallest part of a substance that cannon be broken down chemically.

Ion: An atom or groups of atoms that has an electric charge.

Isotope: Same element different masses

Question 35

How many protons, neutrons, and electrons are within an atom of Nitrogen-14? Within Ca2+-40? Within 35 16 2 2-?

Question 36

How is the modern periodic table arranged and how does it differ from previous periodic tables?

Answer 36

Elements are arranged in increasing atomic number on the modern periodic table while they were arranged in atomic mass/weight in the earlier periodic table.
Sorted by number of protons, each element in the groups or columns have similar characteristics

Question 37

Where are metals, nonmetals, and metalloids located on the periodic table and what are their characteristics properties?

Answer 37

metals occupy the left three-fourths of the periodic table, while nonmetals (except for hydrogen) are clustered in the upper right-hand corner of the periodic table. The elements with properties intermediate between those of metals and nonmetals are called metalloids (or semi-metals).Sep

Question 38

What are the periodic trends as you go down the periodic table for atomic radius and ionization energy?

Answer 38

The atomic radius increases with element size (atomic number)

Question 39

What are valence electrons and why are they important?

Answer 39

The electrons in the outermost shell or energy level of an atom.

Question 40

What is an anion and cation? What are their charges? How do they become negative and positive? What types of elements form each one?

Answer 40

Cation: Ion w/a positive charge, there are more protons than e-s. The atom loses e-s

Anion: ion with negative charge, more e-s than protons. Atoms gained e-s.

Question 41

What is the Octet rule and which elements already satisfy the rule?

Answer 41

Want to get to 8 valence electrons- all atoms want their outer e level to be completely full. - 2 exceptions to Octet rule. H and He only want to 2 electrons. H will almost and always give the 1 e it has.

Question 42

What is the charge of Aluminum will become in order to be stable? Will it gain or lose how many electrons? Would it be a cation or anion?

Answer 42

+3, need to gain 5 electrons, Anion

Question 43

What is the definition for ionic bonding (electrons)? What things come together to make an ionic bond?

Answer 43

IB=m+nm
When 2 ions that are oppositely charged attract to each other.

Metals are loser and non metals are gainers`

Question 44

What is a correct formula unit? What would be the correct formula unit if Lithium and Phosphorus come together? How many electrons would be donated/received and which atom would do which?

Answer 44

Li3P, Li has 1 electron and p has 3. So p gives Li 2 electrons

Question 45

What is the correct formula for Sodium Sulfate? For Beryllium Nitride?

Answer 45

Na2(SO4)

BC3N2

Question 46

What is the correct name for Li3Po4? For CuBr2?

Answer 46

Trilithium Phosphate

Copper Bromide

Question 47

What are the properties/characteristic of ionic bond?

Answer 47

Forming crystal lattice structure, high melting and boiling points, hard, brittle

Question 48

What is the correct formula for Carbonic Acid? What is the correct name for H3P?

Answer 48

H2CO3

hydrofluoric a

Question 49

What is the definition of a covalent bond (electrons)? What things come together to make a covalent bond?

Answer 49

A chemical bond when electrons are shared between two atoms. Two electrons

Question 50

What are the properties/characteristics of polar and non polar covalent bonds?

Answer 50

polar unequal sharing of electrons, creates partial and + - charges higher melting and boiling points, non polar-equal sharing of electrons, no partial charges, lower melting and boiling points

Question 51

How can we differentiate between ionic and covalent bonds?

Answer 51

Ionic- atom donates electrons to other.
Covalent- two atom shares electrons

Question 52

What do the electrons do in a covalent bond?

Answer 52

Share electrons

Question 53

In the molecules above how many shared Paris of electrons are there between and O? How many electrons are around c? How many electrons rare being shared between c and 0? How many lone pairs are around o?

Answer 53

2 shared pairs electrons between c and 0. There are 8 electrons around c. 4 electrons being shared c and o 2 lone pairs around o.

Question 54

What is the difference between non polar covalent, polar covalent and ionic bonds?

Answer 54

If two atoms have an electronegativity difference of 0.4 or less, they form a non-polar covalent bond. If two atoms have an electronegativity difference between 0.4 and 1.8, they form a polar covalent bond. If two atoms have an electronegativity difference of more than 1.8, they form an ionic bond.

Question 55

What is the definition for polarity? What is definition for dipole?