Chem Max learning 2 hours

gonna struggle

Round 76.94098988 to the hundredths place.

76.94

What is 0.30 expressed as a percentage?

30%

Solve and round to the nearest hundredth: (0.33)(37.74) + (0.54)(47.07)

37.87 (12.4542 + 25.4178 = 37.872)

In a neutral atom (no net charge), the number of protons must equal the number of what?

• Electrons

What is the atomic number of an atom with 29 protons, 28 electrons, and 35 neutrons?

• 29 (Atomic number = number of protons)

What is the mass number of an atom with 17 protons, 18 electrons, and 18 neutrons?

• 35 (Mass Number = Protons + Neutrons = 17 + 18)

What is the formula to calculate the atomic mass number?

• Protons + Neutrons (P + N)

Which element has 8 protons?

Oxygen (O)

What is an isotope?

An atom of the same element with a different number of neutrons (and therefore a different mass number).

How do you calculate the weighted average atomic mass of an element's isotopes?

Σ (Isotope Mass × Fractional Abundance) (Example: (23.9850 × 0.7899) + (24.9858 × 0.1000) + (25.9826 × 0.1101) = 24.31 amu)

How many total electrons does a neutral atom of Neon (Ne, atomic number 10) have?

10 electrons

What is a chemical compound? Give an example from: He, NaCl, C, N.

A substance made of two or more different elements chemically bonded together (Example: NaCl).

Identify the element with the electron configuration: 1s² 2s² 2p⁴

Oxygen

• In a flame test, what colors are produced by Copper (Cu) and Lithium (Li) compounds?

• Copper = Green, Lithium = Red

The mass number of an atom is defined as what?

The sum of protons and neutrons

Which two subatomic particles have approximately the same mass?

• Protons and neutrons (both are approximately 1 amu)

• What is the atomic number of a particle with 28 protons, 31 neutrons, and 26 electrons?

• 28 (Atomic number always equals the number of protons)

What is the mass number of a particle with 50 protons, 69 neutrons, and 48 electrons?

119 (Mass number = Protons + Neutrons = 50 + 69)

What is the atomic number of an Iron (Fe) particle with 30 neutrons and 24 electrons?

26 (Iron's atomic number is always 26, meaning it has 26 protons)

What is the atomic number of an Iodine (I) particle with 74 neutrons and 54 electrons?

• 53 (Iodine's atomic number is always 53, meaning it has 53 protons)

How many protons, neutrons, and electrons are in a neutral Copper-64 (⁶⁴Cu) atom?

Protons = 29, Neutrons = 35 (64 - 29), Electrons = 29

What subatomic particle determines the identity of an element?

Protons (the atomic number)

• What is the net charge on a particle with 20 protons, 20 neutrons, and 18 electrons?

2+ (Protons: +20, Electrons: -18 → Net charge: +2)

What is the net charge on a Fluorine (F) particle with 10 neutrons and 10 electrons?

1− (Fluorine has 9 protons; Protons: +9, Electrons: -10 → Net charge: -1)

• Which quantity can vary among neutral atoms of the exact same element?

The number of neutrons (which creates different isotopes of that element).

How do you identify two isotopes of the same element using nuclear notation (^A_Z{X})?

• They have the same atomic number (Z) / proton count, but different mass numbers (A).

Americium (Am, atomic number 95) has 146 neutrons. What is its nuclear symbol?

^{241}_{95}\{Am} (or Americium-241) (Mass Number = 95 + 146 = 241)

How do you calculate the number of neutrons in an atom from its mass number and atomic number?

Number of Neutrons = Mass Number - Atomic Number (p+)

How many neutrons are in an atom of Krypton-80 ($^{80}_{36}\text{Kr}$)?

44 neutrons (80 - 36 = 44)

How do you determine which isotope of an element is the most abundant given its average atomic mass?

The most abundant isotope is the one whose mass number is closest to the average atomic mass on the periodic table.

How many protons, neutrons, and electrons are in a neutral Xenon-129 ($^{129}_{\ 54}\text{Xe}$) atom?

• Protons = 54, Neutrons = 75 (129 - 54), Electrons = 54

• Which statement(s) are true about the Periodic Table?

  I. Elements in a period have similar chemical properties.

  II. Elements in a group have similar chemical properties.

  III. Elements are arranged by increasing atomic number.

Both II and III (Groups/columns share chemical properties; periods/rows do not)

• What is the common name for the elements in Group 18 of the periodic table?

Noble gases

• Which element is located in Period 3, Group 2?

Magnesium (Mg)

Which element is located in Period 2, Group 13?

Boron (B)

Which element has 6 electron shells (Period 6) and 5 valence electrons (Group 15)?

• Bismuth (Bi)

Which element has 5 electron shells (Period 5) and 2 valence electrons (Group 2)?

Strontium (Sr)

What is the name of the alkaline earth metal (Group 2) in Period 7?

Radium (Ra)

What is the name of the halogen (Group 17) in Period 2?

Fluorine (F)

Which halogen is a liquid at standard room conditions?

Bromine (Br)

How can you tell if a chemical symbol represents a single element vs. a compound (e.g., $CO_2$, $CO$, $Co$, $CH_4$)?

• A single element has only one capital letter

The atomic mass of nitrogen is 14.01 amu. Which isotope is most abundant: 12N, 13N, 14N, or 15N?

14N

The atomic mass of helium is 4.003 amu. Which isotope is most abundant: 2He, 3He, 4He, or 5He?

4He

Which element is represented by 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3?

Arsenic (As)

Which element is represented by [Kr] 5s2 4d2?

Zirconium (Zr)

What is the complete electron configuration for Neon (Ne)?

1s2 2s2 2p6

What is the complete electron configuration for Sodium (Na)?

1s2 2s2 2p6 3s1

What is the complete electron configuration for Lithium (Li)?

1s2 2s1

What is the condensed electron configuration for Barium (Ba)?

[Xe] 6s2

What is the condensed electron configuration for Gallium (Ga)?

[Ar] 4s2 3d10 4p1

What is the condensed electron configuration for Selenium (Se)?

[Ar] 4s2 3d10 4p4

Which statements are true about atoms? I. Mostly empty space. II. Nucleus surrounded by negatively charged protons. III. Identity determined by protons in nucleus.

both I and III (protons are positively charged, not negatively charged)

What is the atomic number of a fluorine (F) particle with 10 neutrons and 10 electrons?

9 (Fluorine always has 9 protons)

How many protons, neutrons, and electrons are in a neutral Calcium-44 (44Ca) atom?

Protons: 20, Neutrons: 24, Electrons: 20

The atomic mass of cobalt is 58.93 amu. Which isotope is most abundant?

59Co (58.93 is closest to 59)

Calculate the average atomic mass of Buffandbluvium (Bv) given 104Bv (5.32%), 105Bv (17.75%), and 106Bv (76.93%).

105.72

Which element is represented by 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1?

Gallium (Ga)

What is the difference between a cation and an anion?

A cation is a positively charged ion (lost electrons), and an anion is a negatively charged ion (gained electrons).

What are the maximum electron capacities for the s, p, d, and f subshells?

s = 2, p = 6, d = 10, f = 14

What color flame does Lithium (Li) produce?

Red (Carmine)

What color flame does Sodium (Na) produce?

Bright Yellow

What color flame does Potassium (K) produce?

Lilac (Light Purple)

What color flame does Calcium (Ca) produce?

Orange-Red (Brick Red

What color flame does Strontium (Sr) produce?

Crimson Red

What color flame does Barium (Ba) produce?

Apple Green

What color flame does Copper (Cu) produce?

Green or Blue-Green