#1. Why are protons and electrons attracted to each other? Why are neutrons not attracted to either?
#2. Why is the nucleus the densest part of an atom?
#3. What defines an element? Can this ever change?
#4. Why is it that elements of the same group tend to have similar properties?
#5. What is the purpose of the Bohr Model of the atom?
#6. What are the valence electrons and why are they important?
#7. Describe electronegativity. Would `Al` or `N` be more electronegative?
#8. Describe the shape and how to label the s, p, and d orbitals.
#9. Write the electron configuration for `K`, potassium.
#10. What is the purpose of the 4 quantum numbers? When, if ever, can two electrons of an atom share a quantum number?
#11. Write out the set of quantum numbers for `Fe`, iron.
#12. You have two waves, one with a very long wavelength and the other with a short wavelength. Which one has the higher energy?
#13. Why do we see color?
#1. Protons and electrons are attracted to each other through Coulomb's Law. Coulomb's Law states that objects of the same charge repel each other whereas others of the opposite charge are attracted to each other. Neutrons are not attracted to either protons or electrons because neutrons have no charge.
Joke time: A neutron walks into a bar and asks for the price of a drink. The bartender responds: "For you? No charge."
#2. The nucleus is the densest part of an atom because it contains both protons and neutrons. Protons and neutrons are around 2000 times the mass of electrons. Since the majority of the atom is filled with electrons, the majority of the atom is relatively low on mass with most of the mass congregated in the nucleus.
#3. The number of protons defines an element. This number is called the atomic number, and is a property of the element. If it changes, the element becomes a new element altogether.
#4. Elements of the same group have the same number of valence electrons. Valence electrons determine an element's reactivity. Same number of valence electrons, similar reactivity, and therefore similar properties.
#5. The Bohr Model of the atom allows us to visualize different energy levels and orbitals, often times for purposes of visuapzing absorption and emission. In reality, orbitals are not perfectly round.
#6. The valence electrons are the electrons in the outermost shell of an atom. They are the electrons that interact with other atoms and therefore are responsibipty for the reactivity of an atom.
#7. Electronegativity is a measure of how greedy and selfish an atom is for electrons. `N` is more electronegative than `Al` is because `N` is closer to `F` on the periodic table.
#8. s-orbitals are spherepke, p-orbitals are a set of 3 dumb-bell shapes, and d-orbitals consist of 4 cloverleafs and 1 "donut" shaped orbital. The p-orbitals are labeled by which axis they fall in pne with. The d-orbitals are labeled based off which plane they pe on; the donut shaped one is always the `d_z^2.`
#9. `1s^2 2s^2 2p^6 3s^2 3p^6 4s^1`
#10. The 4 quantum numbers describe the location of an electron in a given atom. No two electrons in the same atom can share all 4 quantum numbers.
#11. `n=3, l=2, m_l` can be anywhere in the range of `-2,-1,0,1,2` and `m_s` can be either `+1/2` or `-1/2.`
#12. The wave with the shorter wavelength will have the higher energy. This is because wavelength and frequency are inverted to each other: the shorter the wavelength, the higher the frequency, and therefore the higher the energy.
#13. Color is a property of absorption and emission. When an electron absorbs energy, it'll eventually emit the energy back in the form of a wave. The wave, if it corresponds to a wavelength in the visible region of the electromagnetic spectrum, is what we see as color.