Inorganic Chemistry/Introduction to Elements

Introduction to Elements

Periodic Table of Elements

An Element is one of a limited class of substances composed entirely of atoms that have an invariant nuclear charge and which cannot be further divided by ordinary chemical methods. Atoms having the same nuclear charge have the same number of protons in the nucleus. This number is called atomic number, denoted as Z, derived from the first letter of name of the greatest Ancient Greek god Zeus. As of May 2011, 118 elements have been found.

An Isotope is a set of atoms that have the same number of protons and neutrons in the nucleus. For example, Element Hydrogen (denoted as H) is a set of atoms that have one proton in their nuclei. This set has 3 subsets (Isotopes): Protium or Hydrogen-1 (the first name is rarely used), Deuterium and Tritium. A protium is an atom that has one proton in its nucleus and no neutrons, while a deuterium not only has one proton but also 1 neutrons. In case of tritium, the number of neutrons is double: 2 neutrons in the nucleus.

In the context of this book, I use lower case for the reference to an object of a set, and use upper case for that set. For example, I use 'Deuterium' when I want to refer to a set of atoms that have one proton and one neutron in the nucleus, and use 'deuterium' when I want to refer to a single atom of the set. I use 'Isotope' for the reference to an Isotope, and 'isotope' to refer to an atom of that Isotope. The same thing for 'Element' and 'element'. Although the name of an element is considered as uncountable, in the scope of this book I use that name as a short-handed version for 'an atom of an Element'. For example 'an atom of Hydrogen' can be written as 'a hydrogen' in this book.

Another note is: every time you want to refer to element and you don't care about the different in the number of neutrons they have, use the Element's name in lower case. If you want to refer to an atom of a specific set of an element, use the Isotope's name in lower case. For example:

1) Water consists of hydrogen and oxygen (I don't care about the isotopes of Hydrogen and Oxygen)

2) A tritium has 1 proton and 2 neutrons in its nucleus (now I care!)

Rule: upper case for set, lower case for object

Element Denotation

The following assumes you have already known the mass and charge of a proton, neutron and electron. If you don't know or you have forgotten, review lesson 1, First Glance At Subatomic Particles

Every Element has a symbol, usually the first letter of its name in English, but sometimes derived from the element's name in Latin or some other language. Hydrogen is H, Oxygen is O, Nitrogen is N etc. This symbol also represents an element (an atom of an Element). A atom of Hydrogen is H, of Oxygen is O and of Nitrogen is N etc. This convention (using the same letter for an Element and an element) is particularly popular in chemical equations. As many other convention in science is not always convenient with all people, this one is not convenient with me since it violates my rule. Nevertheless, you can use any symbols you like as long as you understand the concept. Remember you are learning how the nature works, not how the scientists denote things :)

I use lower case all together when writing chemical equations to avoid confusion. But when I publish it, I use LibreOffice to switch them back to upper case :)

Okay, let's go back to our study. Instead of writing 'Protium', 'Deuterium' or 'Tritium', you can write ¹H, ²H and ³H respectively. The '1', '2', '3' above the H to the left is the mass number, denoted as A, which is the total number of protons and neutrons in the nucleus. Sometimes it can be called more appropriately as nucleon number. I prefer the second name, so I will use it throughout this book. This denotation is particularly useful to refer to an Isotope of an Element

Sometimes you can see the atomic number (the number of protons in the nucleus) written below the nucleon number, as in $_{1}^{1}{\text{H}}$, $_{1}^{2}{\text{H}}$, $_{1}^{3}{\text{H}}$. However, it is not necessary, because the 'H' has already told us that this is a set of atoms having one proton in the nucleus.

Again, the note comes in. When you see ¹H elsewhere apart from this book, it can mean a set of atoms or an atom.

List of Elements

If we define atomic number as the number of protons an atom has in its nucleus, then atomic number should be applied to a specific atom, not a set of atoms. Therefore, the first column is named 'Atomic number of element'.

List of elements

Atomic number of element	Element	Symbol	Group	Period	Block	State at Standard temperature and pressure (STP)	Occurrence	Description
1	Hydrogen	H	1	1	s	Gas	Primordial	Non-metal
2	Helium	He	18	1	s	Gas	Primordial	Noble gas
3	Lithium	Li	1	2	s	Solid	Primordial	Alkali metal
4	Beryllium	Be	2	2	s	Solid	Primordial	Alkaline earth metal
5	Boron	B	13	2	p	Solid	Primordial	Metalloid
6	Carbon	C	14	2	p	Solid	Primordial	Non-metal
7	Nitrogen	N	15	2	p	Gas	Primordial	Non-metal
8	Oxygen	O	16	2	p	Gas	Primordial	Non-metal
9	Fluorine	F	17	2	p	Gas	Primordial	Halogen
10	Neon	Ne	18	2	p	Gas	Primordial	Noble gas
11	Sodium	Na	1	3	s	Solid	Primordial	Alkali metal
12	Magnesium	Mg	2	3	s	Solid	Primordial	Alkaline earth metal
13	Aluminium	Al	13	3	p	Solid	Primordial	Metal
14	Silicon	Si	14	3	p	Solid	Primordial	Metalloid
15	Phosphorus	P	15	3	p	Solid	Primordial	Non-metal
16	Sulfur	S	16	3	p	Solid	Primordial	Non-metal
17	Chlorine	Cl	17	3	p	Gas	Primordial	Halogen
18	Argon	Ar	18	3	p	Gas	Primordial	Noble gas
19	Potassium	K	1	4	s	Solid	Primordial	Alkali metal
20	Calcium	Ca	2	4	s	Solid	Primordial	Alkaline earth metal
21	Scandium	Sc	3	4	d	Solid	Primordial	Transition metal
22	Titanium	Ti	4	4	d	Solid	Primordial	Transition metal
23	Vanadium	V	5	4	d	Solid	Primordial	Transition metal
24	Chromium	Cr	6	4	d	Solid	Primordial	Transition metal
25	Manganese	Mn	7	4	d	Solid	Primordial	Transition metal
26	Iron	Fe	8	4	d	Solid	Primordial	Transition metal
27	Cobalt	Co	9	4	d	Solid	Primordial	Transition metal
28	Nickel	Ni	10	4	d	Solid	Primordial	Transition metal
29	Copper	Cu	11	4	d	Solid	Primordial	Transition metal
30	Zinc	Zn	12	4	d	Solid	Primordial	Transition metal
31	Gallium	Ga	13	4	p	Solid	Primordial	Metal
32	Germanium	Ge	14	4	p	Solid	Primordial	Metalloid
33	Arsenic	As	15	4	p	Solid	Primordial	Metalloid
34	Selenium	Se	16	4	p	Solid	Primordial	Non-metal
35	Bromine	Br	17	4	p	Liquid	Primordial	Halogen
36	Krypton	Kr	18	4	p	Gas	Primordial	Noble gas
37	Rubidium	Rb	1	5	s	Solid	Primordial	Alkali metal
38	Strontium	Sr	2	5	s	Solid	Primordial	Alkaline earth metal
39	Yttrium	Y	3	5	d	Solid	Primordial	Transition metal
40	Zirconium	Zr	4	5	d	Solid	Primordial	Transition metal
41	Niobium	Nb	5	5	d	Solid	Primordial	Transition metal
42	Molybdenum	Mo	6	5	d	Solid	Primordial	Transition metal
43	Technetium	Tc	7	5	d	Solid	Transient	Transition metal
44	Ruthenium	Ru	8	5	d	Solid	Primordial	Transition metal
45	Rhodium	Rh	9	5	d	Solid	Primordial	Transition metal
46	Palladium	Pd	10	5	d	Solid	Primordial	Transition metal
47	Silver	Ag	11	5	d	Solid	Primordial	Transition metal
48	Cadmium	Cd	12	5	d	Solid	Primordial	Transition metal
49	Indium	In	13	5	p	Solid	Primordial	Metal
50	Tin	Sn	14	5	p	Solid	Primordial	Metal
51	Antimony	Sb	15	5	p	Solid	Primordial	Metalloid
52	Tellurium	Te	16	5	p	Solid	Primordial	Metalloid
53	Iodine	I	17	5	p	Solid	Primordial	Halogen
54	Xenon	Xe	18	5	p	Gas	Primordial	Noble gas
55	Caesium	Cs	1	6	s	Solid	Primordial	Alkali metal
56	Barium	Ba	2	6	s	Solid	Primordial	Alkaline earth metal
57	Lanthanum	La	3	6	f	Solid	Primordial	Lanthanide
58	Cerium	Ce	3	6	f	Solid	Primordial	Lanthanide
59	Praseodymium	Pr	3	6	f	Solid	Primordial	Lanthanide
60	Neodymium	Nd	3	6	f	Solid	Primordial	Lanthanide
61	Promethium	Pm	3	6	f	Solid	Transient	Lanthanide
62	Samarium	Sm	3	6	f	Solid	Primordial	Lanthanide
63	Europium	Eu	3	6	f	Solid	Primordial	Lanthanide
64	Gadolinium	Gd	3	6	f	Solid	Primordial	Lanthanide
65	Terbium	Tb	3	6	f	Solid	Primordial	Lanthanide
66	Dysprosium	Dy	3	6	f	Solid	Primordial	Lanthanide
67	Holmium	Ho	3	6	f	Solid	Primordial	Lanthanide
68	Erbium	Er	3	6	f	Solid	Primordial	Lanthanide
69	Thulium	Tm	3	6	f	Solid	Primordial	Lanthanide
70	Ytterbium	Yb	3	6	f	Solid	Primordial	Lanthanide
71	Lutetium	Lu	3	6	d	Solid	Primordial	Lanthanide
72	Hafnium	Hf	4	6	d	Solid	Primordial	Transition metal
73	Tantalum	Ta	5	6	d	Solid	Primordial	Transition metal
74	Tungsten	W	6	6	d	Solid	Primordial	Transition metal
75	Rhenium	Re	7	6	d	Solid	Primordial	Transition metal
76	Osmium	Os	8	6	d	Solid	Primordial	Transition metal
77	Iridium	Ir	9	6	d	Solid	Primordial	Transition metal
78	Platinum	Pt	10	6	d	Solid	Primordial	Transition metal
79	Gold	Au	11	6	d	Solid	Primordial	Transition metal
80	Mercury	Hg	12	6	d	Liquid	Primordial	Transition metal
81	Thallium	Tl	13	6	p	Solid	Primordial	Metal
82	Lead	Pb	14	6	p	Solid	Primordial	Metal
83	Bismuth	Bi	15	6	p	Solid	Primordial	Metal
84	Polonium	Po	16	6	p	Solid	Transient	Metalloid
85	Astatine	At	17	6	p	Solid	Transient	Halogen
86	Radon	Rn	18	6	p	Gas	Transient	Noble gas
87	Francium	Fr	1	7	s	Solid	Transient	Alkali metal
88	Radium	Ra	2	7	s	Solid	Transient	Alkaline earth metal
89	Actinium	Ac	3	7	f	Solid	Transient	Actinide
90	Thorium	Th	3	7	f	Solid	Primordial	Actinide
91	Protactinium	Pa	3	7	f	Solid	Transient	Actinide
92	Uranium	U	3	7	f	Solid	Primordial	Actinide
93	Neptunium	Np	3	7	f	Solid	Transient	Actinide
94	Plutonium	Pu	3	7	f	Solid	Primordial	Actinide
95	Americium	Am	3	7	f	Solid	Synthetic	Actinide
96	Curium	Cm	3	7	f	Solid	Synthetic	Actinide
97	Berkelium	Bk	3	7	f	Solid	Synthetic	Actinide
98	Californium	Cf	3	7	f	Solid	Synthetic	Actinide
99	Einsteinium	Es	3	7	f	Solid	Synthetic	Actinide
100	Fermium	Fm	3	7	f	Solid	Synthetic	Actinide
101	Mendelevium	Md	3	7	f	Solid	Synthetic	Actinide
102	Nobelium	No	3	7	f	Solid	Synthetic	Actinide
103	Lawrencium	Lr	3	7	d	Solid	Synthetic	Actinide
104	Rutherfordium	Rf	4	7	d		Synthetic	Transition metal
105	Dubnium	Db	5	7	d		Synthetic	Transition metal
106	Seaborgium	Sg	6	7	d		Synthetic	Transition metal
107	Bohrium	Bh	7	7	d		Synthetic	Transition metal
108	Hassium	Hs	8	7	d		Synthetic	Transition metal
109	Meitnerium	Mt	9	7	d		Synthetic
110	Darmstadtium	Ds	10	7	d		Synthetic
111	Roentgenium	Rg	11	7	d		Synthetic
112	Copernicium	Cn	12	7	d		Synthetic	Transition metal
113	(Ununtrium)	Uut	13	7	p		Synthetic
114	(Ununquadium)	Uuq	14	7	p		Synthetic
115	(Ununpentium)	Uup	15	7	p		Synthetic
116	(Ununhexium)	Uuh	16	7	p		Synthetic
117	(Ununseptium)	Uus	17	7	p		Synthetic
118	(Ununoctium)	Uuo	18	7	p		Synthetic

Exercises

The following exercises help you utilize the concepts you have learned. Work through them yourself, try to think a way to tackle the problem.

1. How many protons are there in the following atoms: h, fe, cu, al, n, o, c.
2. How many neutrons are there in the following atoms: $^{4}{\text{he}}$, $^{31}{\text{p}}$, $^{130}{\text{ba}}$, $^{23}{\text{na}}$, $^{39}{\text{k}}$, $^{19}{\text{f}}$, $^{22}{\text{ne}}$.
3. Draw an illustration for each of the following atoms: $^{9}{\text{be}}$, $^{24}{\text{mg}}$, $^{25}{\text{mg}}$, $^{26}{\text{mg}}$, $^{32}{\text{s}}$, $^{33}{\text{s}}$, $^{35}{\text{cl}}$, $^{37}{\text{cl}}$. Assume electrons are on a same circle. Draw each proton, neutron and electron as a ball.
4. Specify the name of each of the following atoms. Because of the large atomic number. I draw all protons (and neutrons) as a big ball.

Hints

1. Look up the List of Elements to find the atomic number, which is the number of protons an element has.
2. You see the nucleon number as a left superscript. Look up the List of Elements to find the atomic number. Since the nucleon number is the sum of particles in the nucleus, when you subtract it by the atomic number, you get the number of neutrons the atom has.
3. First you need to look up the atomic number of an element. It is the number of protons the atom has. Subtract it from the nucleon number then you have the number of neutrons. Neutrons and protons make the nucleus of the atom. In normal stage, the number of protons equals the number of electrons in an atom. Draw electrons moving around the nucleus.

Solutions

**1**

element	number of protons
h	1
fe	26
cu	29
al	13
n	7
o	8
c	6

**2**

element	number of neutrons
$^{4}{\text{He}}$	2
$^{31}{\text{P}}$	16
$^{130}{\text{Ba}}$	74
$^{23}{\text{Na}}$	12
$^{39}{\text{K}}$	20
$^{19}{\text{F}}$	10
$^{22}{\text{Ne}}$	12

**3**

element	illustation
$^{9}{\text{be}}$
$^{24}{\text{mg}}$
$^{25}{\text{mg}}$
$^{26}{\text{mg}}$
$^{32}{\text{s}}$
$^{33}{\text{s}}$
$^{35}{\text{cl}}$
$^{37}{\text{cl}}$

**4**

Illustration	element
	$^{7}{\text{li}}$
	$^{55}{\text{mn}}$
	$^{58}{\text{ni}}$
	$^{66}{\text{zn}}$
	$^{51}{\text{v}}$
	$^{42}{\text{ca}}$
	$^{40}{\text{ar}}$

Thinking

This session helps you build your critical thinking. Try to answer yourself, write it down a paper. The answers provided here are only a reference, there may be other answers as well. If you have another answer, feel free to add :)

1. You know the atomic number is denoted as a Z. You also know why scientists choose that letter. But why is the nucleon number denoted as an A?
2. Why are protons, neutrons denoted as p and n respectively?
3. Why are electrons denoted as e^-?
4. Can protons and neutrons be denoted as p⁺ and n⁺ respectively?
5. In the scope of this book, what does an element and an isotope mean? What details are they different from?

Answers to Thinking

1. In convention, the atomic number is written as a subscript to the left of the Element's name, such as in $_{1}{\text{H}}$. The nucleon number is written above it, such as in $_{1}^{1}{\text{H}}$. Nucleon number is the above, atomic number is the below, just the same as 'A' is the first letter, 'Z' is the last.
2. They are denoted after their first letter.
3. Electrons can be denoted as the letter e, just the same as the case of protons and neutrons. But later the scientists found their anti-particles, called positrons. Positrons have almost the same characteristics as electrons, except for the charge. The charge of a positron over the elementary charge is +1, while in case of an electron, -1. Positrons were later named e⁺, electrons e^-
4. Yes, I think protons can be denoted as p⁺ while their anti-particles, p^-. But the neutrons would not. They have no charge, so '+' or '-' doesn't have any meaning. If they were ever denoted like that, there would be other reasons.
5. An element is an atom of an Element. An isotope is an atom of an Isotope. When we say a hydrogen, we refer to an atom that may be a protium, deuterium or tritium. When we say a tritium, we only refer to an atom of Tritium.