Question

protons, neutrons, and electrons practice worksheet
calculating the number of each particle in an atom:

protons = atomic number

electrons = protons

neutrons = atomic mass - atomic number or big # - small #

use the periodic table to find the numbers of protons, neutrons, and electrons for atoms of the following elements.

name of element	element symbol	mass number	atomic number	protons	neutrons	electrons
sodium		24	11
	y	89				39
copper			29		35
	tc	98		43
	pb	207
thallium		204	81
	h					0
carbon		12
	n				7
	ba					56
calcium
	si					14
argon			18
	mg				12	12

Explanation:

Step1: Recall the rules

Number of protons = Atomic number. Number of electrons = Number of protons (for neutral atoms). Number of neutrons = Mass number - Atomic number.

Step2: For Sodium

Atomic number = 11, so number of protons = 11. Number of electrons = 11. Mass number = 24, number of neutrons = 24 - 11 = 13.

Step3: For Y (Yttrium)

Atomic number = 39 (since number of electrons = 39 and electrons = protons for neutral atom). Mass number = 89, number of neutrons = 89 - 39 = 50, number of protons = 39.

Step4: For Copper

Atomic number = 29, so number of protons = 29. Mass number = 29+35 = 64, number of neutrons = 35, number of electrons = 29.

Step5: For Tc (Technetium)

Atomic number = 43, so number of protons = 43. Mass number = 98, number of neutrons = 98 - 43 = 55, number of electrons = 43.

Step6: For Pb (Lead)

Atomic number needs to be looked up (82). Mass number = 207, number of neutrons = 207 - 82 = 125, number of protons = 82, number of electrons = 82.

Step7: For Thallium

Atomic number = 81, so number of protons = 81. Mass number = 204, number of neutrons = 204 - 81 = 123, number of electrons = 81.

Step8: For H (Hydrogen)

If number of neutrons = 0 and assuming a common isotope, atomic number = 1, number of protons = 1, number of electrons = 1, mass number = 1.

Step9: For Carbon

Mass number = 12, atomic number = 6 (from periodic - table), number of protons = 6, number of neutrons = 12 - 6 = 6, number of electrons = 6.

Step10: For N (Nitrogen)

If number of neutrons = 7, atomic number = 7 (from periodic - table), number of protons = 7, mass number = 7 + 7=14, number of electrons = 7.

Step11: For Ba (Barium)

If number of electrons = 56, number of protons = 56 (for neutral atom). Atomic number = 56, assume a common isotope, mass number needs to be looked up (e.g., 137), number of neutrons = 137 - 56 = 81.

Step12: For Calcium

Atomic number = 20 (from periodic - table), number of protons = 20, assume a common isotope with mass number = 40, number of neutrons = 40 - 20 = 20, number of electrons = 20.

Step13: For Si (Silicon)

If number of electrons = 14, number of protons = 14 (for neutral atom). Atomic number = 14, assume a common isotope with mass number = 28, number of neutrons = 28 - 14 = 14.

Step14: For Argon

Atomic number = 18, number of protons = 18, assume a common isotope with mass number = 40, number of neutrons = 40 - 18 = 22, number of electrons = 18.

Step15: For Mg (Magnesium)

Atomic number = 12, number of protons = 12, mass number = 24 (common isotope), number of neutrons = 24 - 12 = 12, number of electrons = 12.

Answer:

Name of Element	Element Symbol	Mass Number	Atomic Number	Protons	Neutrons	Electrons
Sodium	Na	24	11	11	13	11
Yttrium	Y	89	39	39	50	39
Copper	Cu	64	29	29	35	29
Technetium	Tc	98	43	43	55	43
Lead	Pb	207	82	82	125	82
Thallium	Tl	204	81	81	123	81
Hydrogen	H	1	1	1	0	1
Carbon	C	12	6	6	6	6
Nitrogen	N	14	7	7	7	7
Barium	Ba	137	56	56	81	56
Calcium	Ca	40	20	20	20	20
Silicon	Si	28	14	14	14	14
Argon	Ar	40	18	18	22	18
Magnesium	Mg	24	12	12	12	12