Distribution in ocean Radon is present in seawater as the radioactive isotope 222 Rn (half-life of only 3.82 days), which is produced by decay of 226 Ra. 222 Rn is in secular equiilibrium with its parent isotope except near the sediments and at the seasurface. An excess of 222 Rn, relative to the activity of 226 Ra, may occur near the sediment-water interface as radon gas diffuses from.

• Rn Atomic Numbers
• Rn Atomic Number Table
• Rn Atomic Number Calculator
• Rn Element Atomic Number

Balancing Nuclear Equations

To balance a nuclear equation, the mass number and atomic numbers of all particles on either side of the arrow must be equal.

1. Atomic Number of Radon Atomic Number of Radon is 86. Chemical symbol for Radon is Rn. Number of protons in Radon is 86.
2. (A) (1) 226 Ra decays into Rn (atomic number 86) and alpha particle. Complete the 88 reaction written below. Be sure to show the atomic mass number and atomic number of each particle.
3. Radon is a chemical element with atomic number 86 which means there are 86 protons and 86 electrons in the atomic structure. The chemical symbol for Radon is Rn. Neutron Number and Mass Number of Radon Mass numbers of typical isotopes of Radon are 222.

Learning Objectives

Produce a balanced nuclear equation

Key Takeaways

Key Points

• A balanced nuclear equation is one where the sum of the mass numbers (the top number in notation) and the sum of the atomic numbers balance on either side of an equation.
• Nuclear equation problems will often be given such that one particle is missing.
• Instead of using the full equations, in many situations a compact notation is used to describe nuclear reactions.

Key Terms

• baryon: A heavy subatomic particle created by the binding of quarks by gluons; a hadron containing three quarks. They have half-odd integral spin and are thus fermions.

Nuclear reactions may be shown in a form similar to chemical equations, for which invariant mass, which is the mass not considering the mass defect, must balance for each side of the equation. The transformations of particles must follow certain conservation laws, such as conservation of charge and baryon number, which is the total atomic mass number. An example of this notation follows:

[latex]^6_3text{Li} + ^2_1text{H}rightarrow ^4_2text{He} + ?[/latex]

To balance the equation above for mass, charge, and mass number, the second nucleus on the right side must have atomic number 2 and mass number 4; it is therefore also helium-4. The complete equation therefore reads:

[latex]^6_3text{Li} + ^2_1text{H}rightarrow ^4_2text{He} + ^4_2text{He}[/latex]

Or, more simply:

[latex]^6_3text{Li} + ^2_1text{H}rightarrow 2 ^4_2text{He}[/latex]

Lithium-6 plus deuterium gives two helium-4s.: The visual representation of the equation we used as an example.

Compact Notation of Radioactive Decay

Instead of using the full equations in the style above, in many situations a compact notation is used to describe nuclear reactions. This style is of the form A(b,c)D, which is equivalent to A + b gives c + D. Common light particles are often abbreviated in this shorthand, typically p for proton, n for neutron, d for deuteron, α representing an alpha particle or helium-4, β for beta particle or electron, γ for gamma photon, etc. The reaction in our example above would be written as Li-6(d,α)α.

Balancing a Radioactive Decay Equation

In balancing a nuclear equation, it is important to remember that the sum of all the mass numbers and atomic numbers, given on the upper left and lower left side of the element symbol, respectively, must be equal for both sides of the equation. In addition, problems will also often be given as word problems, so it is useful to know the various names of radioactively emitted particles.

Example

[latex]^{ 235 }_{ 92 }text{U} rightarrow ^{ 231 }_{ 90 }text{Th} + ?[/latex]

This could be written out as uranium-235 gives thorium-231 plus what? In order to solve, we find the difference between the atomic masses and atomic numbers in the reactant and product. The result is an atomic mass difference of 4 and an atomic number difference of 2. This fits the description of an alpha particle. Thus, we arrive at our answer:

[latex]^{ 235 }_{ 92 }text{U} rightarrow ^{ 231 }_{ 90}text{Th} + ^{ 4 }_{ 2 }text{He}[/latex]

Example

[latex]^{ 214 }_{ 84 }text{Po} + 2 ^{ 4 }_{ 2 }text{He} + 2^0_{-1}text{e}rightarrow ?[/latex]

This could also be written out as polonium-214, plus two alpha particles, plus two electrons, give what? In order to solve this equation, we simply add the mass numbers, 214 for polonium, plus 8 (two times four) for helium (two alpha particles), plus zero for the electrons, to give a mass number of 222. For the atomic number, we take 84 for polonium, add 4 (two times two) for helium, then subtract two (two times -1) for two electrons lost through beta emission, to give 86; this is the atomic number for radon (Rn). Therefore, the equation should read:

[latex]^{ 214 }_{ 84 }text{Po}+2^{ 4 }_{ 2 }text{He}+2^0_{-1}text{e}rightarrow ^{222}_{86}text{Rn}[/latex]

Writing nuclear equations: Describes how to write the nuclear equations for alpha and beta decay.

Nuclear Binding Energy and Mass Defect

A nucleus weighs less than its sum of nucleons, a quantity known as the mass defect, caused by release of energy when the nucleus formed.

Learning Objectives

Calculate the mass defect and nuclear binding energy of an atom

Key Takeaways

Key Points

• Nuclear binding energy is the energy required to split a nucleus of an atom into its components.
• Nuclear binding energy is used to determine whether fission or fusion will be a favorable process.
• The mass defect of a nucleus represents the mass of the energy binding the nucleus, and is the difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed.

Key Terms

• nucleon: One of the subatomic particles of the atomic nucleus, i.e. a proton or a neutron.
• strong force: The nuclear force, a residual force responsible for the interactions between nucleons, deriving from the color force.
• mass defect: The difference between the calculated mass of the unbound system and the experimentally measured mass of the nucleus.

Binding Energy

Nuclear binding energy is the energy required to split a nucleus of an atom into its component parts: protons and neutrons, or, collectively, the nucleons. The binding energy of nuclei is always a positive number, since all nuclei require net energy to separate them into individual protons and neutrons.

Mass Defect

Nuclear binding energy accounts for a noticeable difference between the actual mass of an atom’s nucleus and its expected mass based on the sum of the masses of its non-bound components.

Recall that energy (E) and mass (m) are related by the equation:

[latex]text{E}=text{mc}^2[/latex]

Here, c is the speed of light. In the case of nuclei, the binding energy is so great that it accounts for a significant amount of mass.

The actual mass is always less than the sum of the individual masses of the constituent protons and neutrons because energy is removed when when the nucleus is formed. This energy has mass, which is removed from the total mass of the original particles. This mass, known as the mass defect, is missing in the resulting nucleus and represents the energy released when the nucleus is formed.

Mass defect (M_d) can be calculated as the difference between observed atomic mass (m_o) and that expected from the combined masses of its protons (m_p, each proton having a mass of 1.00728 amu) and neutrons (m_n, 1.00867 amu):

[latex]text{M}_text{d}=(text{m}_text{n}+text{m}_text{p})-text{m}_text{o}[/latex]

Nuclear Binding Energy

Once mass defect is known, nuclear binding energy can be calculated by converting that mass to energy by using E=mc². Mass must be in units of kg.

Once this energy, which is a quantity of joules for one nucleus, is known, it can be scaled into per-nucleon and per- mole quantities. To convert to joules/mole, simply multiply by Avogadro’s number. To convert to joules per nucleon, simply divide by the number of nucleons.

Nuclear binding energy can also apply to situations when the nucleus splits into fragments composed of more than one nucleon; in these cases, the binding energies for the fragments, as compared to the whole, may be either positive or negative, depending on where the parent nucleus and the daughter fragments fall on the nuclear binding energy curve. If new binding energy is available when light nuclei fuse, or when heavy nuclei split, either of these processes result in the release of the binding energy. This energy—available as nuclear energy—can be used to produce nuclear power or build nuclear weapons. When a large nucleus splits into pieces, excess energy is emitted as photons, or gamma rays, and as kinetic energy, as a number of different particles are ejected.

Nuclear binding energy is also used to determine whether fission or fusion will be a favorable process. For elements lighter than iron-56, fusion will release energy because the nuclear binding energy increases with increasing mass. Elements heavier than iron-56 will generally release energy upon fission, as the lighter elements produced contain greater nuclear binding energy. As such, there is a peak at iron-56 on the nuclear binding energy curve.

Nuclear binding energy curve: This graph shows the nuclear binding energy (in MeV) per nucleon as a function of the number of nucleons in the nucleus. Notice that iron-56 has the most binding energy per nucleon, making it the most stable nucleus.

The rationale for this peak in binding energy is the interplay between the coulombic repulsion of the protons in the nucleus, because like charges repel each other, and the strong nuclear force, or strong force. The strong force is what holds protons and neutrons together at short distances. As the size of the nucleus increases, the strong nuclear force is only felt between nucleons that are close together, while the coulombic repulsion continues to be felt throughout the nucleus; this leads to instability and hence the radioactivity and fissile nature of the heavier elements.

Example

Calculate the average binding energy per mole of a U-235 isotope. Show your answer in kJ/mole.

First, you must calculate the mass defect. U-235 has 92 protons, 143 neutrons, and has an observed mass of 235.04393 amu.

[latex]text{M}_text{d}=(text{m}_text{n}+text{m}_text{p})-text{m}_text{o}[/latex]

M_d = (92(1.00728 amu)+143(1.00867 amu)) – 235.04393 amu

M_d = 1.86564 amu

Calculate the mass in kg:

Rn Atomic Numbers

1.86564 amu x [latex]frac{1 text{kg}}{6.02214times10^{26} text{amu}}[/latex] = 3.09797 x 10-²⁷ kg

Now calculate the energy:

E = mc²

E = 3.09797 x 10^-27 kg x (2.99792458 x 10⁸[latex]frac{text{m}}{text{s}}[/latex])²

E =2.7843 x 10^-10 J

Now convert to kJ per mole:

[latex]2.7843times10^{-10}frac{text{Joules}}{text{atom}} times frac {6.02times10^{23} text{atoms}}{text{mole}}times frac{1 text{kJ}}{1000 text{joules}} =[/latex] 1.6762 x 10¹¹[latex]frac{text{kJ}}{text{mole}}[/latex]

We remember from our school chemistry course that every element has its own specific atomic number. It is the same as the number of protons that the atom of each element has, so sometimes atomic number is called proton number. It is always the whole number and it ranges from 1 to 118, according to the number of the element in the Periodic Table. This number can be really important and something essential to know, in relation to a certain chemical element which is the issue of our interest at the moment.

Why is this so? Why is the atomic number so important? First of all, it is the number that makes elements different from one another as it shows the number of protons in their nuclei. Also, knowing the atomic number of an element can give us an idea about the position of the element in the Periodic Table. Atomic number of an element never changes: for example, the atomic number of oxygen is always 8, and the atomic number of Chlorine is always 18. The atomic number is marked with the symbol Z, taken from a German word zahl (or atomzahl, which is 'atomic number' in German).

This website is created for those who need to know the atomic number of a central chemical element. By using our website, you can do it in just one click and receive short and correct information on this matter. There is also some extra summary on every each chemical element which can be found at our website, including the atomic weight of each element, as well as physical and chemical properties of every element and its importance. Use this website at any time when you need to get fast and precise information about atomic or proton number of chemical elements.

List of chemical elements in periodic table with atomic number, chemical symbol and atomic weight. You can sort the elements by clicking on the table headers. Please click on the element name for complete list of element properties.

Atomic Number	Chemical Symbol	Element Name	Atomic Weight (u)
1	H	Hydrogen	1.008
2	He	Helium	4.003
3	Li	Lithium	6.94
4	Be	Beryllium	9.012
5	B	Boron	10.81
6	C	Carbon	12.011
7	N	Nitrogen	14.007
8	O	Oxygen	15.999
9	F	Fluorine	18.998
10	Ne	Neon	20.18
11	Na	Sodium	22.99
12	Mg	Magnesium	24.305
13	Al	Aluminium	26.982
14	Si	Silicon	28.085
15	P	Phosphorus	30.974
16	S	Sulfur	32.06
17	Cl	Chlorine	35.45
18	Ar	Argon	39.948
19	K	Potassium	39.098
20	Ca	Calcium	40.078
21	Sc	Scandium	44.956
22	Ti	Titanium	47.867
23	V	Vanadium	50.942
24	Cr	Chromium	51.996
25	Mn	Manganese	54.938
26	Fe	Iron	55.845
27	Co	Cobalt	58.933
28	Ni	Nickel	58.693
29	Cu	Copper	63.546
30	Zn	Zinc	65.38
31	Ga	Gallium	69.723
32	Ge	Germanium	72.63
33	As	Arsenic	74.922
34	Se	Selenium	78.971
35	Br	Bromine	79.904
36	Kr	Krypton	83.798
37	Rb	Rubidium	85.468
38	Sr	Strontium	87.62
39	Y	Yttrium	88.906
40	Zr	Zirconium	91.224
41	Nb	Niobium	92.906
42	Mo	Molybdenum	95.95
43	Tc	Technetium	98
44	Ru	Ruthenium	101.07
45	Rh	Rhodium	102.906
46	Pd	Palladium	106.42
47	Ag	Silver	107.868
48	Cd	Cadmium	112.414
49	In	Indium	114.818
50	Sn	Tin	118.71
51	Sb	Antimony	121.76
52	Te	Tellurium	127.6
53	I	Iodine	126.904
54	Xe	Xenon	131.293
55	Cs	Caesium	132.905
56	Ba	Barium	137.327
57	La	Lanthanum	138.905
58	Ce	Cerium	140.116
59	Pr	Praseodymium	140.908
60	Nd	Neodymium	144.242
61	Pm	Promethium	145
62	Sm	Samarium	150.36
63	Eu	Europium	151.964
64	Gd	Gadolinium	157.25
65	Tb	Terbium	158.925
66	Dy	Dysprosium	162.5
67	Ho	Holmium	164.93
68	Er	Erbium	167.259
69	Tm	Thulium	168.934
70	Yb	Ytterbium	173.045
71	Lu	Lutetium	174.967
72	Hf	Hafnium	178.49
73	Ta	Tantalum	180.948
74	W	Tungsten	183.84
75	Re	Rhenium	186.207
76	Os	Osmium	190.23
77	Ir	Iridium	192.217
78	Pt	Platinum	195.084
79	Au	Gold	196.967
80	Hg	Mercury	200.592
81	Tl	Thallium	204.38
82	Pb	Lead	207.2
83	Bi	Bismuth	208.98
84	Po	Polonium	209
85	At	Astatine	210
86	Rn	Radon	222
87	Fr	Francium	223
88	Ra	Radium	226
89	Ac	Actinium	227
90	Th	Thorium	232.038
91	Pa	Protactinium	231.036
92	U	Uranium	238.029
93	Np	Neptunium	237
94	Pu	Plutonium	244
95	Am	Americium	243
96	Cm	Curium	247
97	Bk	Berkelium	247
98	Cf	Californium	251
99	Es	Einsteinium	252
100	Fm	Fermium	257
101	Md	Mendelevium	258
102	No	Nobelium	259
103	Lr	Lawrencium	266
104	Rf	Rutherfordium	267
105	Db	Dubnium	268
106	Sg	Seaborgium	269
107	Bh	Bohrium	270
108	Hs	Hassium	277
109	Mt	Meitnerium	278
110	Ds	Darmstadtium	281
111	Rg	Roentgenium	282
112	Cn	Copernicium	285
113	Nh	Nihonium	286
114	Fl	Flerovium	289
115	Mc	Moscovium	290
116	Lv	Livermorium	293
117	Ts	Tennessine	294
118	Og	Oganesson	294

Rn Atomic Number Table

Lists of Elements in Periodic Table

Rn Atomic Number Calculator

You can also list the elements in various ordered properties with printable tables below.

Lists of Elements by Group Number in Periodic Table

Rn Element Atomic Number

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