Inorganic Chemistry/Introduction to Elements

Introduction to Elements

Periodic Tabe of Elements

An Element is a set of atoms that have the same number of protons in the nucleus. This number is called atomic number, denoted as Z, from the first letter 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. 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 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 else where 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?

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.