Periodic Table In Chemistry


Periodic Table In Chemistry

What is the periodic table and why is it called periodic?

Why is it called the Periodic Table? It is called ‘periodic’ because elements are lined up in cycles or periods. From left to right elements are lined up in rows based on their atomic number (the number of protons in their nucleus).

What are the characteristics of the periodic table?

Characteristics of Groups in a Periodic Table – Moving from top to bottom in a group of the periodic table, that is, moving from top to bottom in a vertical column of the periodic table, we will discuss the variation of some of the important properties of elements including the number of valence electrons, valency, atom size, and metallic character.

  1. These variances will be explained further below.
  2. Valence Electrons Each element in a periodic table group has the same number of valence electrons.
  3. Lithium, sodium, and potassium, for example, all contain one valence electron in their atoms and belong to group 1 of the periodic table.
  4. Lithium, sodium, and potassium atoms can easily lose their one valence electron to create potassium ions with one unit positive charge, Li, Na, and K, respectively.

As a result, group 1 elements are monovalent with a valency of 1. In their atoms, all elements in group 2 have two valence electrons. Except for helium, which has only two valence electrons in its atom, group 13 elements have three valence elements, group 14 elements have four valence electrons, group 15 elements have five valence electrons, group 16 elements have six valence electrons, group 17 elements have seven valence electrons, and group 18 elements have eight valence electrons.

  • As a result, as you move down the periodic table, the number of valence electrons in the elements stays the same.
  • Valency All elements in a group have the same valency because the number of valence electrons that determine valency is the same.
  • Lithium, sodium, and potassium, for example, all have one valence electron, hence all the elements in group 1 have the same valency of one.

Group 1 elements have a valency of 1, group 2 elements have a valency of 2, group 13 elements have a valency of 3, group 14 elements have a valency of 4, group 15 elements have a valency of 3, group 16 elements have a valency of 2, group 17 elements have a valency of 1, and group 18 elements have a valency of 0.

  1. As a result, each group’s valency is the same.
  2. Size of atoms The size of atoms or atomic size grows as one moves down a group of the periodic table.
  3. When we proceed down in group 1 from top to bottom, the size of the atoms gradually increases from lithium to francium.
  4. Every time we proceed from the top to the bottom of a group, a new shell of electrons is added to the atoms.
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As a result, the number of electron shells in the atoms steadily increases, causing the atoms’ size to increase as well. So, the lowest atomic size may be found at the top of the group, while the biggest atomic size can be found at the bottom. For example, in group 1, lithium (Li) is the smallest element, whereas francium (Fr) is the largest element.

Li Smallest atom
Na Atomic size increases on going down the group
Fr Biggest atom

Metallic Character The metallic character of elements increases as you move from top to bottom, while the non-metallic character decreases. The elements in the bottom half of the group have the most metallic character. For instance, the metallic nature of group 1 increases from lithium to francium.

  1. Every time we move down a group of the periodic table, one more electron shell is added, and the size of the atoms grows.
  2. The valence electrons move further away from the nucleus, and the nucleus’ hold on valence electrons weakens.
  3. As a result, the atom can lose valence electrons more quickly and create positive ions, increasing its electropositivity.

Furthermore, as the size of atoms grows larger as they progress through the group, the nucleus becomes more embedded in the atom. The nucleus’ attraction to the incoming electron decreases, making it difficult for the atom to create negative ions and reducing electronegative characteristics.

  • Question 1: Which element has the largest size in the third period? Answer: In a period, the atomic size decreases from left to right.
  • This indicates that the element to the left of the period is the largest, while the element to the right of the period is the smallest.
  • The element on the left in the third period is sodium, hence sodium (Na) has the largest size in the third period.
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Question 2: What is the tendency to lose electrons over a period? Answer: The nuclear charge grows as the number of protons increases over a period, and the valence electrons are drawn in more strongly by the nucleus, making it more difficult for the atoms to lose electrons.

  1. As a result, as a period progresses from left to right, the tendency of atoms to lose electrons decreases.
  2. Question 3: What are the usual valence electrons and valency of the elements of group 2? Answer: The elements of group 2 are beryllium, magnesium, calcium, strontium, barium, radium.
  3. All these elements have electrons in their outermost shell, so the valence electrons of the elements of group 2 are 2.

Since there are two valence electrons,m so these elements can easily lose 2 electrons, hence the valency of the elements of group 2 is 2. Question 4: An element belongs to group 2 of the periodic table, is this element metal or non-metal? Answer: The metallic character of elements decreases as you move from left to right in a period.

Elements Atomic Number Electronic configuration
A 4 2, 2
B 8 2, 6
C 12 2, 8, 2

Clearly, elements A and C have 2 valence electrons. Hence they belong to the same group. : Characteristics of the Periods and Groups of the Periodic Table

What is period law?

The genius of Mendeleev’s periodic table – Lou Serico

The periodic law states: ‘ When elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties.’

What are the main 4 elements?

The four elements of western culture are: EARTH, AIR, FIRE, and WATER, These four elements were believed to be essential to life. Taoism has five elements, each one superior to the next in turn: wood, earth, water, fire, and metal. Metal conquers wood, wood conquers earth, et cetera.

What are the four atoms?

Identify the building blocks of matter – At its most fundamental level, life is made up of matter. Matter is any substance that occupies space and has mass. Elements are unique forms of matter with specific chemical and physical properties that cannot be broken down into smaller substances by ordinary chemical reactions.

  • There are 118 elements, but only 92 occur naturally.
  • The remaining elements are synthesized in laboratories and are unstable.
  • Each element is designated by its chemical symbol, which is a single capital letter or, when the first letter is already “taken” by another element, a combination of two letters.

Some elements follow the English term for the element, such as C for carbon and Ca for calcium. Other elements’ chemical symbols derive from their Latin names; for example, the symbol for sodium is Na, referring to natrium, the Latin word for sodium.

  • The four elements common to all living organisms are oxygen (O), carbon (C), hydrogen (H), and nitrogen (N).
  • In the non-living world, elements are found in different proportions, and some elements common to living organisms are relatively rare on the earth as a whole, as shown in Table 1.
  • For example, the atmosphere is rich in nitrogen and oxygen but contains little carbon and hydrogen, while the earth’s crust, although it contains oxygen and a small amount of hydrogen, has little nitrogen and carbon.
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In spite of their differences in abundance, all elements and the chemical reactions between them obey the same chemical and physical laws regardless of whether they are a part of the living or non-living world.

Table 1. Approximate Percentage of Elements in Living Organisms (Humans) Compared to the Non-living World
Element Life (Humans) Atmosphere Earth’s Crust
Oxygen (O) 65% 21% 46%
Carbon (C) 18% trace trace
Hydrogen (H) 10% trace 0.1%
Nitrogen (N) 3% 78% trace

What are the 3 major properties of elements in the periodic table?

The Key Atomic Properties Atomic properties that are critical to the behavior of elements are electron configuration, atomic size, ionization energy, electron affinity, and electronegativity.

What is the advantage of the periodic table?


It is easier to remember the properties of an element if its position in the periodic table is known. The periodic table has made the study of chemistry systematic and easy. It acts as an aid to memory. The type of compounds formed by an element can be predicted by knowing it position in the periodic table.

What are the 3 categories of the periodic table?

The three major groups on the Periodic Table are the metals, nonmetals and metalloids. Elements within each group have similar physical and chemical properties.

Why is it a periodic table?

Why Is the Periodic Table Important? The periodic table has come a long way since Russian chemist Dmitri Mendeleev first drew up the original sketches in 1869. While plenty has changed over the past 150 years, including the addition of new elements such as Nihonium (Nh), Moscovium (Mc), Tennessine (Ts) and Oganesson (Og) in 2016, the underlying concept of the periodic table retains its relevance and importance.