Question

atomic structure
an atom is made up of protons and neutrons (both found in the nucleus) and electrons (in the surrounding electron cloud). the atomic number is equal to the number of protons.
the mass number is equal to the number of protons plus neutrons. in a neutral atom, the number of protons equals the number of electrons. the charge on an ion indicates an imbalance between protons and electrons. too many electrons produces a negative charge, too few, a positive charge.
this structure can be written as part of a chemical symbol.
example: mass number charge
15n+3 7 protons
8 neutrons (15 - 7)
4 electrons
atomic number
complete the following chart.

element/ion	atomic number	atomic mass	mass number	protons	neutrons	electrons
h+	1	1.008	1	1	0	0
12c	6	12.011	12	6	6	6
7li+	3	6.941	7	3	4	2
35cl-	17	35.453	35	17	18	18
39k	19	39.098	39	19	20	19
24mg2+	12	24.305	24	12	12	10
as3-	33	74.922	75	33	42	36
ag	47	107.868	108	47	61	47
ag+1	47	107.868	108	47	61	46
s-2	16	32.066	32	16	16	18
u	92	238.029	238	92	146	92

Explanation:

Step1: Recall atomic structure rules

Atomic number = number of protons. Mass number = number of protons + number of neutrons. For neutral atoms, number of protons = number of electrons. For ions, adjust electrons based on charge.

Step2: Analyze H

Atomic number of H is 1. Mass number is 1. Protons = 1, Neutrons = 1 - 1=0, Electrons = 1 (neutral atom).

Step3: Analyze H+

Atomic number is 1. Mass number is 1. Protons = 1, Neutrons = 0, Electrons = 1 - 1 = 0 (lost 1 electron for +1 charge).

Step4: Analyze $_{6}^{12}C$

Atomic number is 6. Mass number is 12. Protons = 6, Neutrons = 12 - 6 = 6, Electrons = 6 (neutral atom).

Step5: Analyze $_{3}^{7}Li^{+}$

Atomic number is 3. Mass number is 7. Protons = 3, Neutrons = 7 - 3 = 4, Electrons = 3 - 1 = 2 (lost 1 electron for +1 charge).

Step6: Analyze $_{17}^{35}Cl^{-}$

Atomic number is 17. Mass number is 35. Protons = 17, Neutrons = 35 - 17 = 18, Electrons = 17+1 = 18 (gained 1 electron for - 1 charge).

Step7: Analyze $_{19}^{39}K$

Atomic number is 19. Mass number is 39. Protons = 19, Neutrons = 39 - 19 = 20, Electrons = 19 (neutral atom).

Step8: Analyze $_{12}^{24}Mg^{2 + }$

Atomic number is 12. Mass number is 24. Protons = 12, Neutrons = 24 - 12 = 12, Electrons = 12 - 2 = 10 (lost 2 electrons for +2 charge).

Step9: Analyze $As^{3 - }$

Assume atomic number of As is 33 (from periodic - table). Mass number not given, assume average atomic mass ≈ 75. Protons = 33, Neutrons = 75 - 33 = 42, Electrons = 33+3 = 36 (gained 3 electrons for - 3 charge).

Step10: Analyze Ag

Assume atomic number of Ag is 47 (from periodic - table). Mass number not given, assume average atomic mass ≈ 108. Protons = 47, Neutrons = 108 - 47 = 61, Electrons = 47 (neutral atom).

Step11: Analyze $Ag^{+}$

Atomic number is 47. Mass number is 108. Protons = 47, Neutrons = 61, Electrons = 47 - 1 = 46 (lost 1 electron for +1 charge).

Step12: Analyze $S^{2 - }$

Atomic number of S is 16. Mass number not given, assume average atomic mass ≈ 32. Protons = 16, Neutrons = 32 - 16 = 16, Electrons = 16+2 = 18 (gained 2 electrons for - 2 charge).

Step13: Analyze U

Assume atomic number of U is 92 (from periodic - table). Mass number not given, assume average atomic mass ≈ 238. Protons = 92, Neutrons = 238 - 92 = 146, Electrons = 92 (neutral atom).

Element/Ion	Atomic Number	Atomic Mass	Mass Number	Protons	Neutrons	Electrons
H+	1	1.008	1	1	0	0
$_{6}^{12}C$	6	12.01	12	6	6	6
$_{3}^{7}Li^{+}$	3	6.94	7	3	4	2
$_{17}^{35}Cl^{-}$	17	35.45	35	17	18	18
$_{19}^{39}K$	19	39.10	39	19	20	19
$_{12}^{24}Mg^{2 + }$	12	24.31	24	12	12	10
$As^{3 - }$	33	74.92	75 (assumed)	33	42	36
Ag	47	107.87	108 (assumed)	47	61	47
$Ag^{+}$	47	107.87	108 (assumed)	47	61	46
$S^{2 - }$	16	32.07	32 (assumed)	16	16	18
U	92	238.03	238 (assumed)	92	146	92

Answer:

Element/Ion	Atomic Number	Atomic Mass	Mass Number	Protons	Neutrons	Electrons
H+	1	1.008	1	1	0	0
$_{6}^{12}C$	6	12.01	12	6	6	6
$_{3}^{7}Li^{+}$	3	6.94	7	3	4	2
$_{17}^{35}Cl^{-}$	17	35.45	35	17	18	18
$_{19}^{39}K$	19	39.10	39	19	20	19
$_{12}^{24}Mg^{2 + }$	12	24.31	24	12	12	10
$As^{3 - }$	33	74.92	75 (assumed)	33	42	36
Ag	47	107.87	108 (assumed)	47	61	47
$Ag^{+}$	47	107.87	108 (assumed)	47	61	46
$S^{2 - }$	16	32.07	32 (assumed)	16	16	18
U	92	238.03	238 (assumed)	92	146	92