Final exam

Question 1

What is the difference between physical and chemical change?

Answer 1

A chemical change is a permanent change and it is irreversible in nature.

A Physical change is a temporary change and it is reversible in nature. It affects only physical properties i.e. shape, size, etc. ..

Question 2

When comparing the reactants and products of a chemical reaction, how would you know that a chemical
change has occurred?

Answer 2

There are five signs of a chemical change:
Color Change.
Production of an odor.
Change of Temperature.
Evolution of a gas (formation of bubbles)
Precipitate (formation of a solid)

Question 3

What is the difference between a physical property and a chemical property

Answer 3

• chemical properties are characteristics that describe a substance’s ability to change into different substances
• physical properties are characteristics that can be observed without changing it into another substance.

Question 4

element and a compound

Answer 4

Elements cannot be broken down by chemical reactions. Compounds can be easily separated into simpler substances by chemical reactions.

Question 5

homogeneous and heterogeneous mixtures

Answer 5

Heterogonous mixtures are ones in which their constituents do not mix uniformly, while homogenous mixtures are ones in which they mix uniformly.

Question 6

JJ. Thomson

Answer 6

experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons.

Question 7

Ernest Rutherford

Answer 7

Rutherford’s contribution was the discovery that atoms contain a positively charged nucleus much smaller than the actual atom.

Question 8

John Dalton

Answer 8

Dalton’s atomic theory suggested that all matter was comprised of indivisible and indestructible atoms with distinct masses and properties, the combination of which determined the physical nature of their constituent elements.

Question 9

Mass of electron

Answer 9

0

Question 10

Mass of proton

Answer 10

1

Question 11

Mass of neutron

Answer 11

1

Question 12

What are the only particles that contain mass in an atom, hence, dictate the mass number of an atom?

Answer 12

Together, the number of protons and the number of neutrons determine an element’s mass number: mass number = protons + neutrons.

Question 13

What are the particles responsible for the volume of an atom?~

Answer 13

The volume of the atom as a complete structure, the electrons contribute the most to it with its orbitals.

Question 14

What is a neutral atom?

Answer 14

An atom that has equal number of protons and electrons is called a neutral atom.

Question 15

Isotope

Answer 15

atoms of the same element that have the same number of protons but a different number of neutrons, meaning that their mass number varies

Question 16

How to find neutrons ?

Answer 16

subtracting the atomic number from the atomic mass.

Question 17

What is the difference of the electrons in the 1s orbital compared to the electrons in the 2s orbital of a carbon
atom?

Answer 17

The 2s orbital is at a higher energy level. The 2s orbital can hold more electrons. The 1s orbital can have only one electron.

Question 18

Explain why electrons start filling the 1st energy level of an atom first before they fill the 2nd energy level of
the same atom.

Answer 18

We fill the 1s first because it is lowest in energy, then the 2s because it is next higher in energy, and then the 2p is even higher, and so on.

Question 19

How many total electrons can fit in an s, p, d, f orbitals?

Answer 19

s orbital can contain up to two electrons

p orbital can contain up to six electrons,

the d orbital can contain up to 10 electrons

f orbital can contain up to 14 electrons

Question 20

relationship of nu and lambda in the speed of light formula

Answer 20

Lambda and nu have an inverse relationship.

Question 21

Mendeleev contribution was and the Periodic Law

Answer 21

Mendeleev created his version of the periodic table listing the most known elements at the time by their ascending atomic mass.

Question 22

electronegativity

Answer 22

is a measure of the tendency of an atom to attract a bonding pair of electrons.

Question 23

atomic radius

Answer 23

the total distance from an atom’s nucleus to the outermost orbital of electron

Question 24

ionization energy

Answer 24

a measure of the difficulty in removing an electron from an atom or ion or the tendency of an atom or ion to surrender an electron.

Question 25

key concepts about the different groups – valence electrons, oxidation states

Answer 25

For the main group elements, the valence electron exists only in the outermost electron shell

oxidation state of an element is defined as the formal charge on the atom if all bonds were assumed to be fully ionic

Question 26

metallic vs. non-metallic properties

Answer 26

Metallic character refers to the level of reactivity of a metal.
Non-metallic character relates to the tendency to accept electrons during chemical reactions.

Question 27

period and group

Answer 27

period is a horizontal row of the periodic table. A group is a vertical row of the periodic table

Question 28

Know how to find valence electrons

Answer 28

For neutral atoms, the number of valence electrons is equal to the atom’s main group number

Question 29

calculate the average atomic mass

Answer 29

1. change the percent to a decimal by dividing by 100
2. Multiply the decimal by the isotopes mass
3. Add all the masses together
4. Track the sig figs and put a mark on final answer then once added all together count least amount of decimals