Question

use the following table. (if no information is given about charges or electrons, assume the element is neutral)

isotope symbol	az x notation	mass number	number of protons	number of neutrons	number of electrons	atomic number
calcium	$_{20}^{44}ca^{ + 2}$
iodine - 128
potassium		37	17	20	18	17
$_{16}^{34}s$
		52	24
				21		19
		13	14	13
		209		126
$_{34}^{76}se^{-2}$
			82	122	78

Explanation:

Step1: Recall atomic structure relationships

For an atom or ion represented as $_{Z}^{A}X^{n\pm}$, $A$ is the mass number, $Z$ is the atomic number (equal to number of protons), number of neutrons $N=A - Z$, and number of electrons depends on charge. For a neutral atom, number of electrons = number of protons. For a cation with charge $+n$, number of electrons = number of protons - n. For an anion with charge $-n$, number of electrons = number of protons + n.

Step2: Analyze carbon - 12

Carbon has atomic number $Z = 6$. For carbon - 12 ($_{6}^{12}C$), mass number $A = 12$, number of protons = 6, number of neutrons $N=12 - 6=6$, for neutral atom number of electrons = 6, atomic number = 6.

Step3: Analyze calcium ion $_{20}^{44}Ca^{+2}$

Atomic number $Z = 20$, mass number $A = 44$, number of protons = 20, number of neutrons $N=44 - 20 = 24$, number of electrons = 20 - 2=18, atomic number = 20.

Step4: Analyze iodine - 128

Iodine has atomic number $Z = 53$. For iodine - 128 ($_{53}^{128}I$), mass number $A = 128$, number of protons = 53, number of neutrons $N=128 - 53 = 75$, for neutral atom number of electrons = 53, atomic number = 53.

Step5: Analyze the ion with mass number 37, protons 17

It is chlorine. Mass number $A = 37$, number of protons = 17, number of neutrons $N=37 - 17 = 20$, number of electrons = 18 (since it has a charge to make it an ion as given), atomic number = 17.

Step6: Analyze sulfur $_{16}^{34}S$

Atomic number $Z = 16$, mass number $A = 34$, number of protons = 16, number of neutrons $N=34 - 16 = 18$, for neutral atom number of electrons = 16, atomic number = 16.

Step7: Analyze the atom with mass number 52 and protons 24

It is chromium. Mass number $A = 52$, number of protons = 24, number of neutrons $N=52 - 24 = 28$, for neutral atom number of electrons = 24, atomic number = 24.

Step8: Analyze the atom with neutrons 21 and atomic number 19

Mass number $A=21 + 19=40$, number of protons = 19, number of electrons = 19 (assuming neutral), atomic number = 19.

Step9: Analyze the atom with protons 13 and neutrons 14

Mass number $A=13 + 14 = 27$, number of electrons = 13 (assuming neutral), atomic number = 13.

Step10: Analyze the atom with mass number 209 and neutrons 126

Number of protons $Z=209 - 126 = 83$, number of electrons = 83 (assuming neutral), atomic number = 83.

Step11: Analyze selenium ion $_{34}^{76}Se^{-2}$

Atomic number $Z = 34$, mass number $A = 76$, number of protons = 34, number of neutrons $N=76 - 34 = 42$, number of electrons = 34+ 2=36, atomic number = 34.

Step12: Analyze the atom with protons 82, neutrons 122 and electrons 78

This is a lead ion. Mass number $A=82 + 122 = 204$, atomic number = 82.

Isotope symbol	$_{Z}^{A}X^{n\pm}$ notation	mass number	number of protons	number of neutrons	number of electrons	atomic number
calcium	$_{20}^{44}Ca^{+2}$	44	20	24	18	20
iodine - 128	$_{53}^{128}I$	128	53	75	53	53
-	-	37	17	20	18	17
sulfur	$_{16}^{34}S$	34	16	18	16	16
-	-	52	24	28	24	24
-	-	40	19	21	19	19
-	-	27	13	14	13	13
-	-	209	83	126	83	83
selenium	$_{34}^{76}Se^{-2}$	76	34	42	36	34
-	-	204	82	122	78	82

Answer:

See the above - filled table.