Question

1. what neutral element has an electron configuration of 2 - 3?

a) boron
b) lithium
c) vanadium
d) helium

1. what is the electron configuration of nitrogen?

a) 2 - 8 - 5
b) 2 - 5
c) 2 - 7
d) 7

1. which choice correctly matches each particle with the correct mass (in amu)?

a) proton = 1, neutron = 1, electron = 0
b) proton = 0, neutron = 1, electron = 0
c) proton = 1, neutron = 0, electron = 1
d) proton = + 1, neutron = 0, electron = - 1

1. what is located inside the nucleus of an atom?

a) dna and histones
b) protons and neutrons
c) energy levels and neutrons
d) protons and electrons

1. what is the correct lewis structure for nitrogen?

(1)
(2)
(3)
(4)

1. how many electrons does a neutral atom of silicon have?

a) 3
b) 4
c) 14
d) 28

1. assuming the atom below is neutral, what element does it represent?

a) helium
b) beryllium
c) magnesium
d) calcium

1. which choice correctly matches each particle with the correct charge?

a) proton = + 1, neutron = - 1, electron = 0
b) proton = 0, neutron = + 1, electron = 0
c) proton = - 1, neutron = 0, electron = + 1
d) proton = + 1, neutron = 0, electron = - 1

1. where do electrons exist in the atom?

a) outside the atom
b) in the nucleus
c) next to the neutrons
d) in energy levels or orbitals

1. which set contains elements that all have 7 valence electrons?

a) h, li, k
b) f, cl, br
c) n, o, f
d) ne, ar, kr

Explanation:

• Question 1: The electron configuration \(2 - 3\) means there are \(2+3 = 5\) electrons. Boron has an atomic number of \(5\) (number of electrons in a neutral atom equals atomic number). Lithium has \(3\) electrons (\(2 - 1\) configuration), vanadium has \(23\) electrons, and helium has \(2\) electrons.
• Question 2: Nitrogen has an atomic number of \(7\). The first energy level can hold \(2\) electrons, and the second energy level holds the remaining \(7 - 2=5\) electrons. So the electron configuration is \(2 - 5\).
• Question 3: Protons and neutrons have a mass of approximately \(1\) amu each, and electrons have a mass of approximately \(0\) amu.
• Question 4: The nucleus of an atom contains protons and neutrons. DNA and histones are in cells (not atoms), energy levels are around the nucleus, and electrons are outside the nucleus.
• Question 6: Silicon has an atomic number of \(14\). In a neutral atom, the number of electrons equals the atomic number.
• Question 7: Count the electrons (dots) in the diagram. There are \(4\) electrons (since it's neutral, equal to protons). Beryllium has an atomic number of \(4\). Helium has \(2\) electrons, magnesium has \(12\), and calcium has \(20\).
• Question 8: Protons have a \(+ 1\) charge, neutrons have \(0\) charge, and electrons have \(-1\) charge.
• Question 9: Electrons exist in energy levels or orbitals around the nucleus.
• Question 10: Elements in group \(17\) (halogens) have \(7\) valence electrons. \(F\) (fluorine), \(Cl\) (chlorine), and \(Br\) (bromine) are halogens. \(H, Li, K\) have \(1\) valence electron, \(N\) has \(5\), \(O\) has \(6\), \(F\) has \(7\), and \(Ne, Ar, Kr\) have \(8\) (except \(He\) which has \(2\)) valence electrons.

Answer:

1. A. Boron
2. B. \(2 - 5\)
3. A. Proton = 1, Neutron = 1, Electron = 0
4. B. Protons and Neutrons
5. C. 14
6. B. Beryllium
7. D. Proton = +1, Neutron = 0, Electron = -1
8. D. In energy levels or orbitals
9. B. \(F, Cl, Br\)