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Subatomic Particles and Isotopic Notation

from- http://learning.mgccc.cc.ms.us/pk/sciencedocs/subatomicparticles.htm

Proton (p⁺) is positively charged particle of the atomic nucleus. The atomic number of an element represents the number of protons in the nucleus.

Electron (e^-) is negatively charged particle that can occupy a volume of space (orbital) around an atomic nucleus. All atoms of an element have the same number of electrons (i.e. any Chlorine atom is going to have 17 electrons). Electrons can be shared or transferred among atoms.

Atoms have an equal number of protons and electrons; therefore, they have a no net charge.

Ion is an atom that has gained or lost one or more electrons, thus becoming positively or negatively charged.

Neutron is an uncharged particle of the nucleus of all atoms EXCEPT hydrogen. For a given element, the mass number is the number of protons and neutrons (nucleons) in the nucleus.

Isotope is one of two or more forms of atoms of an element that differ in their number of neutrons. They have the same atomic number (same number of protons and electrons), but a different mass number due to more or fewer neutrons.

Particle	Charge	Relative Charge**	Mass	Relative mass**	Location
Proton	+1.60 x 10^-19 C	+1	1.672 x 10^-24 g	1 amu	nucleus
Electron	-1.60 x 10^-19 C	-1	9.05 x 10^-28 g	0 amu ~(1/1840 amu)	electron cloud (orbital)
Neutron	neutral	0	1.674 x 10^-24 g	1 amu	nucleus

**Using relative charges and masses are used to keep calculations simple.

Atomic Number

The atomic number is the number of protons in the nucleus of an atom. It is listed on the periodic table for each element. No two elements have the same atomic number (or the same number of protons), so the atomic number identifies the element.(symbol: Z)

Mass Number

Mass number: (symbol: A) total number of protons and neutrons in the nucleus (not listed on the periodic table, since it varies).

NOTE this number is a whole number. Atomic Mass is different.

Atoms of the same element have the same atomic number, but may have different mass numbers.

Isotopic notation for a particular atom (also called nuclide symbol notation):

^A	E
^Z

(E = element's symbol; A = mass number; Z = atomic number)
For example:

²³	Na
¹¹

Represents a sodium atom which always has 11 protons and in this case has a mass number of 23.
(Note: This means that there are 12 neutrons. 23 - 11 = 12)

Mass number - atomic number = # neutrons

Determining the number of electrons-

The number of electrons in an element can change. For a neutral atom, the number of protons is exactly equal to the number of electrons. So the number of electrons is the same as the atomic number. However, it is possible to remove electrons and not change the identity of an element. These are called ions. The charge on the ion tells you the number of electrons.

If the charge is positive, subtract that number from the atomic number to get the number of electrons. You have more protons.

If the charge is negative, add the amount of charge to the atomic number to get the number of electrons. You have more electrons.

Determine the number of protons, neutrons, and electrons present in each of the following atoms.

(mass # = top number, atomic # = bottom number)

^{a)
28}

a protons = 14, electrons = 14, neutrons = 14

¹⁴

^{b) 197}

b p = 79, e = 79, n = 118

⁷⁹

^{c)
40}

c p = 18, e = 18, n = 22

¹⁸

^{d)
64}

d p = 29, e = 29, n = 35

²⁹

^{e)
39}

e p = 19, e = 19, n = 20

¹⁹

^f) 133

f p = 55, e = 55, n = 78

⁵⁵

Identify atoms that are isotopes in each of the following sets of four atoms.

^A)⁸⁰

⁸²

⁸¹

A ⁸⁰

⁸²

³⁵

³⁶

³⁵

^B)¹⁹

¹⁹

¹⁷

²⁰

B ¹⁹

¹⁷

⁹

¹⁰

⁹

⁸

⁹

^C)²³

²⁴

²⁵

C all

¹¹

^D)⁷⁰

⁷⁰

D none

³³

³⁴

³¹

³²

W tThe symbol, atomic number and atomic mass for the atoms with the following characteristics.

1. Contains 15 neutrons and 13 protons.

1. ²⁸

¹³

b) 2. Atomic number is 41. Neutrons 52.

2. ⁹³

⁴¹

c) 3. Contains 33 electrons and 42 neutrons.

3. ⁷⁵

³³

d) 4. Iron contains 84 subatomic particles.

4. ⁵⁸

²⁶

5. Rubidium that contains 87 nucleons.

5. ⁸⁷

³⁷

6. An ion with 17 protons, 18 neutrons and 18 electrons?	6. 35	Cl	1-
	17
7. An ion with atomic number 16, mass number of 32 and 18 electrons?	7. 32	S	2-
	16
8. An atom with number of neutrons 15 and mass number 33?	8. 33	Ar
	18
9. Copper that lost 2 electrons and has 30 neutrons.	9. 59	Cu	2+
	29
10. Hydrogen that has 2 neutrons and no electrons.	10. 3	H	+
	1

Complete the Table Highlight to Reveal Answers

isotopes		# protrons	# neutrons	# electrons
85	Rb⁺	37	48	36
37
119	Sn⁴⁺	50	69	46
50
13	C^4-	6	7	10
6
235	U	92	143	92
92
24	Na⁺	11	13	10
11
223	Fr⁺	87	136	86
87

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