Periodic Table: Classification of Elements in the Periodic Table

len Alfred Ajibola - Tue, 26th March, 2019 @ 18:15: PM

Topics in Chemistry

Le Chatelier's Principle: Changes in Concentration and Pressure explained in Dynamic Equilibrium Chemical Equilibrium: Dynamic Equilibrium in Chemistry Static and Dynamic Equilibrium explained with their Differences Chemistry Scheme of Work, SS1, First Term Chemistry Scheme of Work, SS1, Second Term Chemistry Scheme of Work, SS1, Third Term Compounds in Chemistry: Characteristics of Compounds Types of Mixture: Homogenous and Heterogeneous Mixtures Mixtures: Characteristics of Mixtures Physical Properties of Matter explained with Examples Chemical Properties of Matter explained with Examples Differences between Physical and Chemical Change Ionic Theory and Electrolysis Physical and Chemical Properties of Acids States of Matter: Characteristics of Solids Liquid State of Matter: Characteristics of Liquids Gaseous State of Matter: Characteristics of Gases Molar Mass, Worked Examples and Differences with Molecular Mass Elements: Characteristics of Elements Salts and Types of Salt in Chemistry

Academic Questions in Chemistry

Please check out our Test Your Knowledge page to see all Questions and Answers

The Separating Funnel is a technique used in the separation of mixtures. Another name for Separating Funnel is the _____ Funnel.

  • A. Partition
  • B. Separatory
  • C. Division
  • D. Liquid
  • E. Half
  • F. Dividing

2NH4+(aq) + Ag+(aq) -> 2H4AgN

The equation above represents _____ acid.

  • A. Svante Arrhenius'

  • B. Brønsted–Lowry's

  • C. Gilbert Lewis'

  • D. Avogadro's

  • E. Sir Isaac Newton's

  • F. Albert Einstein's

According to Brønsted Thomas Martin Lowry, an acid is defined as _____.

  • A. Any substance that produces hydrogen ion (H+) when dissolved in water

  • B. A substance that accepts electron pair in a chemical reaction

  • C. A substance that gives out hydronium ion (H3O+) when dissolved in water

  • D. A substance that donates a proton in a chemical reaction

  • E. A substance that reacts with a base to form salt and water

  • F. A substance whose hydrogen ions  (H+) are displaced after a reaction with metals higher in the activity, reactivity or electrochemical series

Which of the following is NOT a characteristic of chemical change?

  • A. A new thing is formed
  • B. It cannot be easily separated into it's constituents elements
  • C. A new chemical formula accompanies whatever is formed
  • D. The burning of candle is an example of a chemical change
  • E. Blood is an example of a chemical change
  • F. Iron rust is an example of a chemical change

Which of the following statement is FALSE concerning a physical change _____.

  • A. Substances formed in a physical change have a unique chemical formula and IUPAC name
  • B. It's a change that is easily reversible
  • C. It's a change that can be separated via an appropriate separation technique
  • D. No new substance is formed
  • E. A mixture of salt and water is a physical change
  • F. Physical change can result to a change in color and shapes of substances

The following substances will sublime EXCEPT _____.

  • A. Sodium Cryolite
  • B. Solid Carbon(IV)oxide
  • C. Arsenic
  • D. Sulphur
  • E. Iodine Crystals
  • F. Naphthalene

Which of the following is a state of matter?

  • A. Ions
  • B. Plasma
  • C. Compounds
  • D. Molecules
  • E. Atoms
  • F. None of the above

The ideal way of separating a mixture of blood is through _____.

  • A. Chromatography
  • B. Fractional Distillation
  • C. Centrifugation
  • D. Filtration
  • E. Separating Funnel
  • F. Fractional Crystallization



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Periodic Table:

The periodic Table (also called periodic table of elements or Mendeleev's table) is the table that shows an organized arrangement of the 118 chemical elements according to their atomic number.

Atomic Number is the number of protons in the nucleus of an atom.

Out of the 118 elements; elements 1 - 94 are present in nature while elements 95 - 118 are synthesized artificially.

The manner at which elements are arranged on this table reveals some similarities in their electronic configuration and chemical properties.

Please read on the Physical Properties of Metals here.

On the Periodic Table, atomic symbol of elements are used to represent each element; for instance, the element sodiun is represented as Na.

Note: The atomic number of each element of the periodic table can be seen on the top left (or on top) of each atomol symbol. Also seen are the elements' atomic mass, just below the atomic symbol.

Atomic Mass is the sum of protons and neutrons in the nucleus of an atom.

Below is a diagram that shows the periodic table of elements:

Periodic Table - Len Academy

Please read on Acids - Physical and Chemical Properties of Acids here.


Classification of elements on the Periodic Table

  • Groups

The vertical columns of the periodic table are called the Groups (up - down).

The groups are 8 in numbers (numbered I, II, III, IV, V, VI, VII and VIII). They appear to be the most significant criteria in the classification of elements in the periodic table.

Most of the elements within a group have similar chemical properties and share a common name. For instance, the group VIII elements are referred to as the noble or rare or inert gases while groups I, II and VII are called alkali metals, alkali earth metals and halogens respectively.

All elements in the same group have the same valence electron(s); for instance, all group "I" elements have one valence electron while group "II" elements have got two.

Valence Electrons(s) is/are the number of electron(s) in the outermost shell of an atom.

Valence Electron - Len Academy

The outermost electrons (valence electrons) determine the chemical behaviour of elements, giving rise to the basis of the periodic law.

The Periodic Law states that the properties of the elements are a periodic functions of their atomic numbers.

To simply put it, elements with the same valence electron(s) will tend to chemically behave in a similar way.

Please read on Organic Chemistry here.


  • Periods

The horizontal rows of the periodic table make up the periods (left - right). They also show some similar trends; for instance, all elements in period one have got one shell while elements in period two have two shells or atomic orbitals.

Note: Electrons revolve round the shell.

As we go across the period, the number of electrons increases by "1".


  • Blocks

Elements in the periodic table are also classified into blocks depending on the electrons present on the outermost shell of the of elements. For this reason, we have the following blocks of elements:

  • s-block elements
  • p-block elements
  • d-block elements
  • f-block elements

Note: Understanding how the electronic configurations of elements are written for their respective blocks is important.

Please read on Salts in Chemistry here.

Apart from the above classifications, elements in the periodic table can further be classified as:

  • Transition metals
  • Lanthanides
  • Actinides

Note: As a student, understanding the chemical properties and trends that elements share within a group and period is vital.

The chemical trend seen in the Periodic Table include:

  • Atomic Radius
  • Ionic Radius
  • Ionization Energy
  • Electronegativity
  • Electron Affinity

An article will be written to explain these terms, including the periodic law.

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Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.

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Amazing facts in Chemistry

The only letters that failed to appear on the periodic table are letters:

J     &     Q

Gold and copper are the only two non-silvery colored metals.

Please read some interesting facts about gold here

Copper is the only metal that is naturally antibacterial. This is why you would see some children utilize 'copper' water bottles in schools

Water actually freezes faster when it’s warm than when it’s cold

Most element in their pure state exists physically in different forms. For instance, pure carbon can exist as both diamond and graphite. This phenomenon is called allotropy.

Please read on modification of Dalton's atomic theory here.

If you pour a handful of salt into a full glass of water, the water level will go down rather than overflowing the glass.

Similarly, if you mix half liter of water and half litre of alcohol, the total volume of the liquid will be les than one litre


Gold ; Len Academy

Below are some facts about gold

  • It is the only metal that has a gold (golden) color.

  • Gold is present inside the earth crust in all the seven continents.

  • Pure gold is soft and very stretchable (It can even be stretched into threads).

  • The Latin name of Gold is aurum which means 'shining dawn'. For this reason, its chemical symbol is 'Au'.

  • Gold is a very good conductor of electricity. This is why it’s sometimes used in making USB and audio cables.

  • Gold is non toxic and can be eaten with food. It is sometimes added to desserts in some expensive restaurants.

  • The term Gold originated from an ancient English word 'geolu' which means yellow.

  • 24karat gold is the purest gold element.

Please read more interesting facts about gold here

An acid is a substance that produces Hydrogen ions (H+) when dissolved in water (or when in the form of an aqueous solution).

Svante Arrhenius definition of Acid


An acid is a substance that donates a proton in a chemical reaction.

Brønsted Thomas Martin Lowry definition of Acid


An acid is a substance that accept an electron pair in a chemical reaction.

Gilbert Newton Lewis definition of Acid


Finally, Acids can also be also defined as substances that gives out hydronium ion (H3O+) when dissolved in water.


In summary, all acids will always contain the positive H+ (cation) and an anionic group in their formula. For instance, the acid HCl (Hydrogen Chloride) contains H+ as cation and Cl- as its anion.

Please read the explanations of the above definitions of acid here