How is the periodic table of the elements arranged?
Arrangement of elements in the Periodic Table
Figure shows the Periodic Table in use today.
Elements are arranged horizontally In ascending order of their proton numbers, from 1 to 116, in the Periodic Table.
Groups
- Definition: Each vertical column of elements in the Periodic Table is known as a group.
- Elements with the same number of valence electrons are arranged in the same group.
- There are 18 vertical columns of elements in the Periodic Table known as Group 1, Group 2, until Group 18.
- Group 1 elements are known as alkali metals.
- Group 2 elements are known as alkaline earth metals.
- Group 3 to Group 12 elements are known as transition elements.
- Group 17 elements are known as halogens.
- Group 18 elements are known as noble gases.
Periods
- Definition: Each horizontal row of elements in the Periodic Table is known as a period.
- There are 7 horizontal rows of elements in the Periodic Table, known as Period 1, Period 2, until Period 7.
- Periods 1 to 3 are short periods while Periods 4 to 7 are long periods.
- Period 1 contains 2 elements.
- Periods 2 and 3 contain 8 elements respectively.
- Periods 4 and 5 contain 18 elements respectively.
- Period 6 contains 32 elements.
- Period 7 contains 27 elements.
- Although Period 6 contains 32 elements, elements with proton numbers 57 to 71 are arranged separately at the bottom of the Periodic Table. This series of elements is called lanthanides.
- Similarly, elements with proton numbers 89 to 103 in Period 7 are arranged separately at the bottom of the Periodic Table. This series of elements is called actinides.
Metallic and non-metallic properties
- Element in Group 1, 2 and 13 are metals.
- Transition elements in Group 3 to 12 are also metals.
- Elements in Group 15, 16, 17 and 18 are non-metals.
- In Group 14,
- Carbon and silicon are non-metals.
- Germanium is a metalloid (semimetal)
- Tin and lead are metals.
1. Relationship between the electron arrangement and the position of the element in the Periodic Table
Figure shows the electron arrangements of the elements with proton numbers 1 to 20 in the Periodic Table.
2. Relationship between the electron arrangement and the group number of an element
- Based on above Figure, the group number of an element is determined by the number of valence electrons in an atom of the element.
- Table shows the relationship between the number of valence electrons and the group number of an element.
- For elements with 1 or 2 valence electrons,
Group number of that element = Number of valence electrons - For elements with 3 to 8 valence electrons,
Group number of that element = Number of valence electrons plus 10
Note:
Helium with an electron arrangement of 2 is placed in Group 18. This is an exception.
This is because helium has similar inert properties as the other noble gases in Group 18.
Example: Element Q has a nucleon number of 27. An atom of element Q contains 14 neutrons. In which group is element Q located in the Periodic Table?
Solution:
Number of electrons in an atom Q = Number of protons
= 27 – 14 = 13
Electron arrangement of atom Q = 2.8.3
Number of valence electrons = 3
∴ Group number = 3 + 10 = 13
Hence, element Q is located in Group 13 of the Periodic Table.
3. Relationship between the electron arrangement and the period number of an element
- Based on above Figure, the period number of an element is determined by the number of shells occupied with electrons in an atom of that element.
- Table shows the relationship between the number of shells occupied with electrons and the period number of an element.
- Hence,
Period number of an element = Number of shells occupied with electrons in an atom of that element
Example: Element T has a proton number of 19 and a nucleon number of 39. In which period is element T located in the Periodic Table?
Solution:
Number of electrons in atom T
= Number of protons in atom T
= Proton number =19
∴ Electron arrangement of atom T = 2.8.8.1
Atom T has 4 shells occupied with electrons. Hence, element T is located in Period 4 of the Periodic Table.
Example: Element R is located in Group 15 and Period 3 of the Periodic Table. What is the electron arrangement of an atom of element R?
Solution:
Atom R has 5 valence electrons because it is in Group 15.
Atom R has 3 shells occupied with electrons because it is in Period 3.
Electron arrangement of atom R = 2.8.5
4. Elements with the same number of valence electrons will exhibit similar chemical properties.
For example:
Atom W with an electron arrangement of 2.8.2 and atom X with an electron arrangement of 2.8.8.2 exhibit similar chemical properties.
This is because both the atoms of W and X have 2 valence electrons, that is the same number of valence electrons.
Periodic Table Mnemonics
Mnemonics are easy-to-remember lines or phrases one can use to memorize things that are difficult to learn. In this article, you will find Hindi mnemonics – one each for one group – to learn the Periodic Table
The Periodic Table provides the names, atomic numbers, symbols and atomic weights of known elements. It serves as a great tool for solving chemistry problems.
A periodic table is divided into groups (columns), where elements with each group behave similarly while bonding with other elements; and periods (rows), where elements in one period have same number of electron shells.
Here are some fun, interesting and naughty mnemonics in Hindi used by the backbenchers to memorize elements along each group or period:
Key To Reading These Mnemonics Or Hindi Sentence:
• These sentences contain letters denoting symbols of elements in the same order as they occur in a group or period.
• The symbols have been highlighted as bold letters in the sentence. However at the places where the complete symbol could not be included in the sentence, the first letters have been strung together and the second letter is shown in brackets. While reading the sentence you don’t have to read the letters in bracket. Just keep them in mind.
• At some places, phonetics have been used to denote a symbols such as ‘c’ could be replaced by ‘k’,’g’ with ‘j’, ‘I’ with ‘ea’ and ‘o’ with ‘u’, to make the sentence easier to remember.
S-Block Elements
Consisting of the first two groups, S-block elements have quite similar physical and chemical properties. The valence electrons of the elements in this block occupy s-orbitals.
Group 1 is known as alkali metals. It includes Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Ru), Caesium (Cs), and Francium (Fr).
Mnemonic for Group 1: LiNa Ki Ruby Cse Friendship hai.
Group 2 is known as alkaline earth metals. It includes Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Br), and Radium (Ra).
Mnemonic for Group 2: Beta Mange Car Scooter Baap rone se Raazi
P-Block Elements
Consisting of last six groups of the periodic table (Groups 13 to 18), P-block elements have their valence electrons occupying p-orbitals. This block consists of non-metals, semi-metals and poor metals.
Group 13 is known as Boron group or the group of Icosagens or Triels. It includes Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), and Thallium (Tl).
Mnemonic for Group 13: B A G I T.
Group 14 is known as Carbon group or the group of Crystallogens, Tetragens or Tetrels. It includes Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn), and Lead (Pb).
Mnemonic for Group 14: Chemistry Sir Gives Sanki Problems.
Group 15 is known as the group of Pnictogens or Nitrogen group. It includes Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi).
Mnemonic for Group 15: Nahi Pasand Aise Sab Bhai.
Group 16 is known as the group of Chalcogens or Oxygen group. It includes Oxygen (O), Sulphur (S), Selenium (Se), Tellurium (Te), and the radioactive element Polonium (Po).
Mnemonic for Group 16: Oh! Style Se Tel Polish.
Group 17 is known as the group of Halogens. It includes Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At).
Mnemonic for Group 17: Fir Call kar Bahaar AayI Aunty.
Group 18 is known as the group of Noble gases, excluding Helium. Normally, they are all odorless and colorless gases with very low chemical reactivity. The group includes Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and the radioactive Radon (Rn).
Mnemonic for Group 18: He Never Arrived; Kara Xero Run pe out.
D-Block Elements
D-Block elements consist of element groups 3 to 12 that correspond to the filling of the d-orbital subshell of the second outermost shell. Groups 3 to 11 are also known as transitional metals. Group 12 elements, which have its d subshell completely filled, are also known as post-transition elements.
D-block elements and F-block elements show considerable similarities across the periods too.
We can memorize these elements across the periods:
Period 4 elements are quite stable and many of them are very common in earth’s crust or core or both. D-block elements it includes are Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu) and Zinc (Zn).
Mnemonic for Period 4: Science Ti(ea)cher Vineeta Criplani Man Fenko (FeCo) Ni Kyun(Cu) Zaan hai?
Read as: Science Teacher Vineeta Kriplani manfenko ni kyun zaan hai?
Period 5 elements are known to fill their 5s shell first, then 4d shells and then 5p shells, with rhodium being the exception. The elements of this period show many exceptions to Maledung rule. D-block elements it includes are Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Pd (Palladium), Silver (Ag) and Cadmium (Cd).
Mnemonic for Period 5: Yeh Zarra Nabi bana Mohabaat mein T(c)eri, R(u)o R(h)o P(d)ukarogi Aaj(g) ise Chandni
Read as: Yeh Zarra Nabi bana Mohabbat mein Teri, Ro Ro Pukarogi Aaj ise Chandni
Period 6 includes the lanthanides or rare earths. Some of these transition metals are very valuable such as gold. D-block elements it includes are Lutetium (Lu), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au) and Mercury (Hg).
Mnemonic for Period 6: L(u)a HafTa Warna Reh Us(Os) Irritating Popat ke saath Aur Hoj(g)a pagal.
Read as: La Hafta Warna Reh Us Irritating Popat ke saath Aur Hoja pagal.
Period 7 contains the radioactive elements only. It includes actinides which include the heaviest naturally occurring element Californium. All other elements are synthesized artificially. D-block elements
it includes are Actinium (Ac), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs), Meitnerium (Mt), and Darmstadtium (Ds).
Mnemonic for Period 7: Ak(c)ele R(f) D(b) S(g)harma ki B(h)ook mein H(s)ain Maths ke Difficult sawaal.
Read as: Akele R D Sharma ki Book mein Hain Maths ke Difficult sawaal.
F-Block Elements
F-block elements have their valence electrons in f-orbitals. They are also known as inner transition elements. They can be divided into Lanthanides (also known as rare earth elements) and Actinides that are highly reactive to halogens and chalcogens like lanthanides but they react more easily.
Lanthanides include Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb) and Lutetium (Lu).
We can learn all these in three parts:
- Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), and Samarium (Sm)
Mnemonic for Lanthanides Part 1: Celina aur Priety Ne dande se Pammy aur Simmy ko mara.
- Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), and Holmium (Ho)
Mnemonic for Lanthanides Part 2: Europe G(d)aya to TB(b) aur Di(y)arrohoea Ho gaya.
Read as: Europe Gaya to TB aur Diarrohoea Ho gaya.
- Erbium (Er), Thulium (Tm), Ytterbium (Yb) and Lutetium (Lu)
Mnemonic for Lanthanides Part 3: E re, dekh Tamatar Yellow aur bLue hain.
Actinides include these f-block elements – Thorium (Th), Protactinium (Pa), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk), Fermium (Fm), Mendelevium (Md), Nobelium (No), and Lawrencium (Lr).
We can learn all these in three parts too:
1.Thorium (Th), Protactinium (Pa), Uranium (U), and Neptunium (Np)
Mnemonic for Actinides Part 1: Thode Pehelwan Unse Niptengey.
2.Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk)
Mnemonic for Actinides Part 2: Purane Aam K(C)am Bikenge.
Read as: Purane Aam Kam Bikenge.
- Fermium (Fm), Mendelevium (Md), Nobelium (No), and Lawrencium (Lr)
Mnemonic for Actinides Part 3: ItniFamily aMdani mein No Ladki rajee.