Periodic Table Trends- Atomic size, Melting & Boiling Point Trend

The modern periodic table is based on the law that the properties of an element are a periodic function of their atomic number. These properties are related to the electronic configuration of the elements.

We observe a common trend in properties as we move across a period from left to right or down the group. This trend in properties is known as periodic properties.

The important periodic properties are atomic size, metallic character, non-metallic character, ionization potential, electron affinity, and electronegativity.

Periodic Table Trends:

The following trend in periodic properties of elements is observed:

Atomic size Trends:

The distance between the centre of the nucleus and the outermost shell of an atom is known as the atomic radius. In a group the atomic size increases due to the addition of shells as we move from one period to another. Across a period the atomic size decreases as the number of shells remain the same while the nuclear charge increases. This leads to the pulling of electrons from the outermost shell towards the nucleus thereby decreasing the size.

Metallic character Trends:

The elements which lose electrons to form cations are known as metals. Metallic character increases as we move down the group because the atomic size increases which lead to easy loss of electrons. On the other hand, it decreases across a period as we move from left to right. This happens because there is an increase in nuclear charge which makes it difficult for an atom to lose electrons.

Non-metallic character Trends:

The elements which have a tendency to gain electrons are known as non-metals. The tendency to gain electrons increases on moving across a period due to an increase in the nuclear charge and a decrease in the atomic size.  Hence, non-metallic character increases across a period. As we move down the group the non-metallic character decreases due to an increase in the atomic size.

Ionization potential Trends:

Ionization potential is defined as the amount of energy required to remove an electron from the outermost shell of a gaseous atom and convert it into a positively charged gaseous ion. The periodic properties in terms of ionization potential increase because the atomic size decreases across a period due to an increase in the nuclear charge. When we move down the group, ionization potential decreases due to the increase in atomic size.

Melting Point Trends:

The melting point of an element is basically the energy required to change the state of an element from its solid state to its liquid state. Which essentially implies breaking a few bonds. Thus, higher the stronger the bond between the atoms, the higher will be the melting point. Let us look at the elements in the ascending order of their melting points.

Melting Point	Element	Atomic Number
-272	Helium  (He)	2
-259	Hydrogen (H)	1
-249	Neon (Ne)	10
-220	Fluorine  (F)	9
-218	Oxygen  (O)	8
-210	Nitrogen N	7
-189	Argon Ar	18
-157	Krypton Kr	36
-112	Xenon Xe	54
-101	Chlorine Cl	17
-71	Radon Rn	86
-39	Mercury Hg	80
-7	Bromine Br	35
27	Francium Fr	87
29	Cesium Cs	55
30	Gallium Ga	31
39	Rubidium Rb	37
44	Phosphorus P	15
64	Potassium K	19
98	Sodium Na	11
113	Sulphur S	16
114	Iodine I	53
157	Indium In	49
180	Lithium Li	3
217	Selenium Se	34
232	Tin Sn	50
254	Polonium Po	84
271	Bismuth Bi	83
302	Astatine At	85
303	Thallium Tl	81
321	Cadmium Cd	48
327	Lead Pb	82
420	Zinc Zn	30
449	Tellurium Te	52
630	Antimony Sb	51
639	Magnesium Mg	12
640	Neptunium Np	93
640	Plutonium Pu	94
660	Aluminium Al	13
700	Radium Ra	88
725	Barium Ba	56
769	Strontium Sr	38
795	Cerium Ce	58
816.8	Arsenic As	33
822	Europium Eu	63
824	Ytterbium Yb	70
827	Nobelium No	102
839	Calcium Ca	20
860	Einsteinium Es	99
900	Californium Cf	98
920	Lanthanum La	57
935	Praseodymium Pr	59
937	Germanium Ge	32
962	Silver Ag	47
986	Berkelium Bk	97
994	Americium Am	95
1010	Neodymium Nd	60
1050	Actinium Ac	89
1064	Gold Au	79
1072	Samarium Sm	62
1083	Copper Cu	29
1100	Promethium Pm	61
1132	Uranium U	92
1245	Manganese Mn	25
1278	Beryllium Be	4
1311	Gadolinium Gd	64
1340	Curium Cm	96
1360	Terbium Tb	65
1410	Silicon Si	14
1412	Dysprosium Dy	66
1453	Nickel Ni	28
1470	Holmium Ho	67
1495	Cobalt Co	27
1522	Erbium Er	68
1523	Yttrium Y	39
1527	Fermium Fm	100
1535	Iron Fe	26
1539	Scandium Sc	21
1545	Thulium Tm	69
1552	Palladium Pd	46
1568	Protactinium Pa	91
1627	Lawrencium Lr	103
1656	Lutetium Lu	71
1660	Titanium Ti	22
1750	Thorium Th	90
1772	Platinum Pt	78
1852	Zirconium Zr	40
1857	Chromium Cr	24
1890	Vanadium V	23
1966	Rhodium Rh	45
2150	Hafnium Hf	72
2200	Technetium Tc	43
2250	Ruthenium Ru	44
2300	Boron B	5
2410	Iridium Ir	77
2468	Niobium Nb	41
2617	Molybdenum Mo	42
2996	Tantalum Ta	73
3045	Osmium Os	76
3180	Rhenium Re	75
3410	Tungsten W	74
3500	Carbon C	6
	Mendelevium Md	101
	Rutherfordium Rf	104
	Dubnium Db	105
	Seaborgium  Sg	106
	Bohrium Bh	107
	Hassium Hs	108
	Meitnerium Mt	109
	Darmstadtium Ds	110
	Roentgenium Rg	111
	Copernicium Cn	112
	Nihonium Nh	113
	Flerovium Fl	114
	Moscovium Mc	115
	Livermorium Lv	116
	Tennessine Ts	117
	Oganesson Og	118

Boiling Point Trends:

Just like how the strength of the bonds between atoms affect the Melting Point, the boiling point depends on the heat energy required to create a transition from liquid to gaseous state. Have a look at this table with the elements of the periodic table arranged in order of increasing boiling points.

Boiling  point	Element	Symbol	Atomic number
-269	Helium	He	2
-253	Hydrogen	H	1
-246	Neon	Ne	10
-196	Nitrogen	N	7
-188	Fluorine	F	9
-186	Argon	Ar	18
-183	Oxygen	O	8
-153	Krypton	Kr	36
-108	Xenon	Xe	54
-62	Radon	Rn	86
-35	Chlorine	Cl	17
58.8	Bromine	Br	35
184	Iodine	I	53
280	Phosphorus	P	15
337	Astatine	At	85
357	Mercury	Hg	80
445	Sulphur	S	16
613	Arsenic	As	33
677	Francium	Fr	87
678	Cesium	Cs	55
685	Selenium	Se	34
688	Rubidium	Rb	37
760	Potassium	K	19
765	Cadmium	Cd	48
774	Potassium	K	19
883	Sodium	Na	11
907	Zinc	Zn	30
962	Polonium	Po	84
990	Tellurium	Te	52
1090	Magnesium	Mg	12
1140	Barium	Ba	56
1347	Lithium	Li	3
1384	Strontium	Sr	38
1457	Thallium	Tl	81
1466	Ytterbium	Yb	70
1484	Calcium	Ca	20
1560	Bismuth	Bi	83
1597	Europium	Eu	63
1727	Thulium	Tm	69
1737	Radium	Ra	88
1740	Lead	Pb	82
1750	Antimony	Sb	51
1900	Samarium	Sm	62
1962	Manganese	Mn	25
2000	Indium	In	49
2212	Silver	Ag	47
2270	Tin	Sn	50
2355	Silicon	Si	14
2403	Gallium	Ga	31
2467	Aluminium	Al	13
2510	Erbium	Er	68
2550	Boron	B	5
2562	Dysprosium	Dy	66
2567	Copper	Cu	29
2607	Americium	Am	95
2672	Chromium	Cr	24
2720	Holmium	Ho	67
2732	Nickel	Ni	28
2750	Iron	Fe	26
2807	Gold	Au	79
2830	Germanium	Ge	32
2832	Scandium	Sc	21
2870	Cobalt	Co	27
2927	Palladium	Pd	46
2970	Beryllium	Be	4
3000	Promethium	Pm	61
3041	Terbium	Tb	65
3127	Praseodymium	Pr	59
3127	Neodymium	Nd	60
3200	Actinium	Ac	89
3233	Gadolinium	Gd	64
3235	Plutonium	Pu	94
3257	Cerium	Ce	58
3287	Titanium	Ti	22
3315	Lutetium	Lu	71
3337	Yttrium	Y	39
3380	Vanadium	V	23
3469	Lanthanum	La	57
3727	Rhodium	Rh	45
3818	Uranium	U	92
3827	Platinum	Pt	78
3900	Ruthenium	Ru	44
3902	Neptunium	Np	93
4377	Zirconium	Zr	40
4527	Iridium	Ir	77
4612	Molybdenum	Mo	42
4790	Thorium	Th	90
4827	Carbon	C	6
4877	Technetium	Tc	43
4927	Niobium	Nb	41
5027	Osmium	Os	76
5400	Hafnium	Hf	72
5425	Tantalum	Ta	73
5627	Rhenium	Re	75
5660	Tungsten	W	74
	Protactinium	Pa	91
	Curium	Cm	96
	Berkelium	Bk	97
	Californium	Cf	98
	Einsteinium	Es	99
	Fermium	Fm	100
	Mendelevium	Md	101
	Nobelium	No	102
	Lawrencium	Lr	103
	Rutherfordium	Rf	104
	Dubnium	Db	105
	Seaborgium	Sg	106
	Bohrium	Bh	107
	Hassium	Hs	108
	Meitnerium	Mt	109
	Darmstadtium	Ds	110
	Roentgenium	Rg	111
	Copernicium	Cn	112
	Nihonium	Nh	113
	Flerovium	Fl	114
	Moscovium	Ms	115
	Livermorium	Lv	116
	Tennessine	Ts	117
	Oganesson	Og	118