Semester One Exam

Question 1

What is the difference between physical and a chemical change?

Answer 1

A physical change consists of only changing physical properties while a chemical change results in an entirely new chemical.

Question 2

What is the difference between reactants and products in a chemical reaction?

Answer 2

reactants - addends (left side of equation)
products - what the addends yield (right side of equation)

Question 3

How do you know the difference between a physical and a chemical change?

Answer 3

a chemical change will result in a different chemical structure

Question 4

What is a metal and where is it on the period table?

Answer 4

High electrical and thermal conductivity
Malleability
Ductility
High reflectivity of light
left of the staircase

Question 5

What is a nonmental and where is it on the period table?

Answer 5

Lack all the metallic attributes.
Are good insulators of heat and electricity.
Are mostly gases, sometimes liquids, and occasionally solids at room temperature.
Do not display the properties of metals, such as being malleable, ductile, or good conductors of heat and electricity
right of the staircase

Question 6

What is a metalloid and where is it on the period table?

Answer 6

semiconductors
brittle solids
staircase
(Boron, Silicon, Germanium, Arsenic, antimony, Tellurium, Polonium, Selenium, Astatine)

Question 7

What is the difference between qualitative and quantitative?

Answer 7

qualitative - quality (just normal adjectives)
quantitative - quantity (numbers)

Question 8

What is the difference between precision and accuracy?

Answer 8

Precision - how close each measurement is to all of the other measurements
Accuracy - how close each measurement is to the correct value / goal

Question 9

What is the Law of Definite Proportions?

Answer 9

The fact that a chemical compound contains the same element in exactly the same proportions by mass regardless of the size of the sample or source of the compound.

Question 10

What is the nucleus of an atom?

Answer 10

A region in the center of an atom that is positively charged and consisted of positively charged protons and neutrons of no charge.

Question 11

What is the location of an electron?

Answer 11

The electron cloud

Question 12

What is the charge of an electron?

Answer 12

-1

Question 13

What is atomic number?

Answer 13

The number of protons in one atom of an element

Question 14

What is mass number?

Answer 14

The sum of all the particles in and atom of the average isotopes. Electrons are so small that you do not count them, so it is the sum of protons and neutrons. Because isotopes exist, neutrons are an average.

Question 15

What are isotopes?

Answer 15

Atoms with a different number of neutrons than protons.

Question 16

How do isotopes relate to mass number and neutrons?

Answer 16

The sum of all the particles in an atom of the average isotopes is mass number. Electrons are so small that you do not count them, so it is the sum of protons and neutrons. Because isotopes exist, neutrons are an average.

Question 17

What was Louis de Brogle’s contribution to the quantum model?

Answer 17

He created the duality theory which states that electrons behave both like particles and like waves.

Question 18

What do quantum numbers describe?

Answer 18

The character of an electron

Question 19

What are the four quantum numbers and what do they describe?

Answer 19

1. Principle - shell
2. Angular - shape (spdf)
3. Magnetic - orientation
4. Spin - spin

Question 20

Know how to do electron configuration and what it means

Answer 20

Know how to do electron configuration and what it means

Question 21

Based on period law, explain which elements are most similar given three elements.
What factors may cause atoms to be similar?

Answer 21

Electronegativity
Nonmetal, metal, or metalloid
Group
Period
Number of Valence electrons
Ionization energy

Question 22

Why do atoms form chemical bonds?

Answer 22

Atoms want to have a full valence shell so they react with other atoms so that they can have a full valence shell. This causes chemical bonds.

Question 23

Use examples to show how properties and classifications of elements change as you move across a period.
Going left to right across a period, what changes?

Answer 23

Atoms get smaller because they have more protons and electrons that are pulling on each more strongly and causing the atom to be smaller
Electronegativity goes up (how much the atom attracts electrons)
Ionization energy goes up (force it takes to remove an electron)
*Going from top to bottom in a group it becomes easier to remove an electron (ionization energy) (this is because there are more shells between the protons and electrons so the pull on each other is not as strong and it is easier to lose electrons)

Question 24

Explain nuclear charge and how it affects the general trend in radii of atoms going from left to right across the periodic table.

Answer 24

Atoms get smaller because they have more protons and electrons that are pulling on each more strongly and causing the atom to be smaller

Question 25

What is Avogadro's number?

Answer 25

6.022 x 10^23 atoms per mole

Question 26

How do you convert moles to grams?

Answer 26

When given the amount of an element in moles, multiply by the atomic mass of that element (already in grams) all over one mole. Ex. What is the mass of 0.28 mol of iron? 0.28 mol Fe / 1g = 55.84g Fe / 1 mol Fe = 15.64g Fe

Question 27

How does noble gas configuration work?

Answer 27

Start at the noble gas before the element you want and put the symbol in brackets. Then write the rest of the electron configuration.

Question 28

How do the up down arrows work for an orbital diagram?

Answer 28

draw all of the up arrows first, then go back and add down arrows to create pairs. each letter of spdf... has a set of arrows

Question 29

Using an orbital diagram, how do you determine what element you are looking at?

Answer 29

Look at the spdf... levels and see how many arrows are in the last letter.

Question 30

Know how to create a Lewis dot structure for an atom and an ion.

Answer 30

Know how to create a Lewis dot structure for an atom and an ion.

Question 31

ESSAY 1: How do properties of elements change when moving from left to right in a period? Use examples to support your answer (4-5 sentences).

Answer 31

-Moving from left to right there is one more proton and electron in each atom. This causes a stronger attraction between the proton and electrons causing the nuclear radii to be smaller as the particles draw closer to each other. Ex. - Iron has one less proton and one less electron than Cobalt therefore Cobalt has a smaller nuclear radius because the particles are more attracted to each other and in return closer to each other. -Increasingly less reactive until you get to the halogens Ex. - Potassium is more reactive than Iron because of the number of valence electrons. -Goes from metals to metalloids to nonmetals Ex. - Potassium is a metal, Germanium is a metalloid, and Krypton is a nonmetal -Electronegativity goes up (how much the atom attracts electrons) Ionization energy goes up (force it takes to remove an electron)

Question 32

ESSAY 2: What can you determine about an atom's atomic structure if you are given its atomic number and atomic mass?

Answer 32

-Number of neutrons ~ = amu - # of protons -What element it is -Dictates period and group -Dictates metal, nonmetal, or metalloid -Number of protons ~ = atomic number -Number of electrons ~ = atomic number -Isotope average ~ =amu - # of protons -Number of valance electrons ~ = atomic number separated by how many electrons go in each shell -Dictates properties relative to the reactivity of the element -Dictates what group number, number of shells, how malleable it may be, whether or not it is a good conductor or a semiconductor, electronegativity, atomic radii, ionization energy, etc.