Gen Chem 1 Exam Study Guide Topics / Questions (Ch. 1 & 2)

Label the diagram with its appropriate label from the choices below:

• Mixture

• Pure substance

• Compound

• Element

• Heterogenous

• Homogeneous

A → Pure substance

B → Element

C → Compound

D → Mixture

E → Heterogeneous

F → Homogeneous

Understand the structure of an atom – what are the three subatomic particles?

Proton, neutron, electron

What is the charge on each of the three subatomic particles, where each is located in the atom, and what are the relative masses of each?

Proton

• Charge - Positive (+1)

• Location - Nucleus

• Mass - Relatively the same but slightly less dense than neutron (~1 amu)

Neutron

• Charge - Neutral (0)

• Location - Nucleus

• Mass - Relatively the same but slightly more dense than proton (~1 amu)

Electron

• Charge - Negative (-1)

• Location - Electron cloud

• Mass - the mass of an electron is so small that it is often considered insignificant for the purposes of this class (~0.00055 amu)

Which atomic particles are in the nucleus?

Answer: PROTONS AND NEUTRONS

Explanation: the electrons exist outside the nucleus

How does nuclear size of an atom compare to the atomic size?

The nucleus makes up an extremely small portion of the atom as a whole.

The ______ tells you the identity of the element.

atomic number / number of protons

How do you determine the number of protons, electrons, and neutrons for a given element?

The number of protons is given by the atomic number, the number of neutrons is the mass number minus the atomic number, the number of electrons is the same as the number of protons for a neutrally charged element.

Label the following groups with their common names:

Red group = ?

Blue group = ?

Yellow Group = ?

Green Group = ?

Purple Group = ?

Red group = Alkali metals

Blue group = Alkaline Earth metals

Yellow Group = Transition Metals

Green Group = Halogens

Purple Group = Noble gases

Understand the definition of a mole as it relates to atoms and molecules.

What is a mole?

A mole represents 6.023*10^23 of any given particle, such as an atom, molecule, electron, photon, etc.

A mole is a conversion factor that can be used to covert from moles to particles.

A chemist’s “baker’s dozen”

The value of the mole is equal to the number of atoms in exactly 12 grams of pure C-12.

Be able to determine the number of moles given the number of atoms/molecules or the number of atoms/molecules given the number of moles.

Calculate the number of copper atoms in 2.45 mol of copper.

2.45 mol Cu * (6.022 × 10²³ Cu atoms / 1 mol Cu) = 1.48 × 10²⁴ Cu Atoms

Be able to determine the number of moles given the number of atoms/molecules or the number of atoms/molecules given the number of moles.

A pure silver ring contains 2.80 × 10²² silver atoms. How many moles of silver atoms does it contain?

2.80×10²² Ag atoms * (1 mol / 6.022 × 10²³ Ag atoms) = 0.465 mol Ag

How do you determine the molar mass of an element?

We locate the molar mass of that element on the periodic table. It is provided in units of g/mol.

How many moles of Kr are contained in 349 mg of Kr?

A) 4.75 × 10^-3 moles Kr

B) 33.4 moles Kr

C) 2.11 × 10^-4 moles Kr

D) 2.99 × 10^-3 moles Kr

E) 1.19 × 10^-4 moles Kr

Answer:
A) 4.75 × 10^-3 moles Kr

Explanation:

convert to grams: 349mg = 349/1000 g = 0.349 g

Molar mass of Kr = 83.798 g / mol

Calculate moles of Kr:
0.349 g Kr / 83.797 g/mol Kr = 0.00475 mol Kr

Also be able to combine these conversions

to convert to number of atoms/molecules given the molar mass of a substance and vice versa

Calculate the mass (in g) of 2.0 × 10²⁴ atoms of Hg.

A) 3.9 × 10² g

B) 2.4 × 10² g

C) 3.2 × 10² g

D) 1.5 × 10² g

E) 6.5 × 10² g

Answer:

E) 6.5 × 102 g

Explanation:

First convert atoms to moles using Avogadro’s number.

2.0×1024 atoms / 6.022×1023 atoms/mol = 3.3 mol

Then convert moles to grams using molar mass

(200.59 g/mol) * (3.3 mol) = about 6.5 × 102 grams

Match the following with the diagram and relate them to the properties of light.

• Amplitude

• Wavelength

A = Amplitude
The amplitude is a measure of light intensity
Larger amplitude = brighter light

B = Wavelength
The wavelength of light determines its color (intensive physical property).

Define the wavelength and frequency of a wave.

Wavelength:

• A measure of the distance covered by the wave

• The wavelength of light determines its color (intensive physical property).
  

Frequency:

• The number of waves that pass a point in a given period of time

Define the wavelength and frequency of a wave.

The wavelength and frequency of

electromagnetic waves are _____ proportional.

• ____ wavelength → ____ frequency

• ____ wavelength → ____ frequency

The wavelength and frequency of

electromagnetic waves are inversely proportional.

• Long wavelength → low frequency

• Short wavelength → high frequency

v = c / lambda

How do the various regions of the electromagnetic

spectrum relate to each other?

Wavelength increases as frequency decreases, and vice versa.
ROYGBIV

Red = largest wavelength of visible light
→
Violet = smallest wavelength of visible light

Radio is lowest energy
gamma is highest energy

Einstein observed that when light is shined on a metal surface,

electrons are produced from the surface.

– The electrons emitted from the metal surface are photoelectrons.

– This phenomenon is called the ___________ effect.

photoelectric

A _________ is an electron that has been transferred energy via a photon.

This relates to the idea that “light is quantized”.
Meaning, light does not behave as a continuous entity but instead exists as discrete ______ of energy called photons.

Photons ≠ electrons
Photons are without _____, while electrons have it.

photoelectron, packets, mass

What does it mean for something (like mass, light, or energy) to be quantized?

To be quantized means that a property, such as energy, light, or electric charge, can only exist in discrete, indivisible units called "____". Instead of varying continuously, like a ramp, a quantized property exists in distinct steps, like a staircase.

quanta

“________“ means that the atom could have only very

specific amounts of energy

Quantized

What are the subshell shapes for each value of l (s, p, d, f)?

s: ?
p: ?
d: ?
f: ?

The subshell shape of:

1. s is spherical

2. p is like a dumbbell (two-lobed)

3. d is like a 4-leafed clover or a dumbbell with a donut in the middle

4. f is 8 lobed or two lobed orbital with a donut under each lobe

How many orbitals are in each of the following sublevels?

s: ?
p: ?
d: ?
f: ?

s has 1 orbital (boxes) 0
p has 3 orbitals (boxes) -1, 0, 1
d has 5 orbitals (boxes) -2, -1, 0, 1, 2
f has 7 orbitals (boxes) -3, -2, -1, 0, 1, 2, 3

What is the difference between atomic mass and mass number?

The mass number is the count of protons and neutrons

The atomic mass is the weighted average of naturally occurring isotopes.