Unit 1: Topic 5 - Atomic Structure & Electron Configuration

Question 1

List the three subatomic particles that make up an atom and where they exist within the atom.

Answer 1

An atom is made up of protons, neutrons, and electrons. Positively charged protons exist with neutrally charged neutrons in a densely packed space in the middle of the atom called the nucleus. Negatively charged electrons are much smaller than protons and neutrons (more than 1800x smaller), but protons and electrons have the same magnitude of charge. Electrons exist in a space outside the nucleus called the electron cloud in mathematically determining density maps called orbitals.

The nucleus makes up less than 0.01% of the volume of the atom, meaning most of an atom is empty space where electrons can be.

Diagram of the structure of an atom

Question 2

What are the three main subatomic particles that make up an atom, and what are their respective charges?

Answer 2

Protons- Positive charge. Neutrons- No charge. Electrons- Negative charge.

Question 3

What are the two particles that make up the nucleus of an atom?

Answer 3

Protons and neutrons are the particles that form the nucleus.

Question 4

Use Coulomb’s law and your general knowledge of chemistry to justify the following 2 statements.

1. The force of attraction between Mg2+ and O2- is greater than the force of attraction between Na+ and F-.
2. The force of attraction between K+ and Br- is greater than the force of attraction between Rb+ and I-.

Answer 4

According to Coulomb’s Law, the force of attraction between two charged particles increases as you increase the magnitude of the charges and decreases exponentially as you increase the distance between the two particles.

1. Mg2+ and O2- are both ions with a charge of magnitude 2, while Na+ and F- both have magnitudes of only 1. Since the force of attraction increases with greater charge magnitudes, Mg2+ and O2- face greater attraction.
2. K+ and Br- are smaller ions than Rb+ and I-. This allows the distance between K+ and Br- to be smaller, thus facing an exponentially greater force of attraction than Rb+ and I- even though all four ions have a charge magnitude of 1.

Question 5

Suppose two compounds have equal ionic radii of 10nm, but the first set of ions have charges of 1+ and 1-. The other ions have charges of 3+ and 3-. Which has greater force between the two?

Answer 5

Since the atomic radii are10nm, we can square the value to get 100. We can then multiply the charges to get our greater force. Since the first set has 1 and -1, we multiply those for a numerator of -1. We then divide it by 100 to get -1/100 or -0.01, which will then be multiplied by our Coulomb Constant (k). For the second compound, we have charges of 3 and -3, and multiplying those gives us a numerator of -9. Dividing by 100 gives us -9/100 or -0.09, which will also be multiplied by the Coulomb Constant. Although it will be a “smaller” number, the charges will be more significant as the negative value means they attract each other.

Question 6

What does the Aufbau principle state?

Answer 6

It states that in a ground state of an atom, the electrons will always fill the lowest energy subshell before moving to shells of higher energy.

Question 7

What are inner and outer electrons called?

Answer 7

Inner electrons are called core electrons, and outer electrons are called valence electrons.

Question 8

Where can electrons be found in atoms and ions?

Answer 8

In atoms and ions, the electrons can be thought of as being in “shells (energy levels)” and “subshells (sublevels),” as described by the electron configuration.

Question 9

What is ionization energy?

Answer 9

Ionization energy is defined as the amount of energy (typically measured in Joules or electronvolts) that is required to either strip an element of an electron or to form a shared bond with it.

Question 10

Using your knowledge of ionization energy, rank the following elements in terms from greatest to least in terms of the second ionization energy level.

1. Sodium (Na)
2. Magnesium (Mg)
3. Oxygen (O)
4. Rubidium (Rb)

Answer 10

Greatest- Sodium (Na), 4562 kJ/mol
2nd- Oxygen (O), 3388 kJ/mol
3rd- Rubidum (Rb), 2633 kJ/mol
Least- Magnesium (Mg), 1451 kJ/mol