Awareness of the general concepts in Chemistry is part of the IBPS PO, SBI PO and SSC exams. In the IBPS exams, Basic Chemistry Awareness will be checked. This article will introduce many such concepts of Basic Chemistry Awareness. Let us improve our Basic Chemistry Awareness.
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Basic Chemistry Awareness
In the SBI mains, the section of the questions on general awareness can contain these questions. The most basic concept in chemistry is that all matter is composed of atoms. The questions will usually not have any formulae involved but would be conceptual. Some of the important concepts that have a high probability of appearing in the exam are as follows:
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Periodic Table Of Elements
All matter is composed of atoms. Atoms are very small and are the smallest elements of matter that represent the properties of a substance. The atoms of a similar kind form an element. When two or more elements combine chemically together, they form a compound. In a compound, atoms of different elements are held together by strong forces of attraction that we call the chemical bonds.
There are about 118 known elements, out of which about 94 occur naturally on earth. These elements are mainly put into the categories of metals, non-metals and metalloids. Most of the elements are present in the solid state at the room temperature (25 C). However, Hg (Mercury) and Br (Bromine) which are in the liquid state at the room temperature. There are many gaseous elements also like the Noble gases viz: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Ra) and the element 118 or Ununoctium (Uuo). The elements Hydrogen (H), He (Helium), Nitrogen, Oxygen and the halogens viz – Fluorine (F), Chlorine (Cl), Krypton (Kr), Xenon (Xe) and Radon (Rn) are in the gaseous state.
The elements are all arranged in a table as per their physical and chemical properties. This period is the Modern Periodic Table. The physical and chemical properties of the elements are a property of their atomic numbers.
Atoms
Every atom has a structure. By this, we mean that each atom has a central positively charged part. We call this the nucleus. The nucleus is made up of smaller positively charged particles or the protons. Outside the nucleus, even smaller negatively charged particles move about the nucleus. These particles are the electrons. The number of protons in the nucleus of an atom is the atomic number of the atom. In an electrically neutral atom, the number of protons is equal to the number of electrons.
Atoms combine together by strong forces known as the chemical bonds. Every substance that you see around you comprises of atoms.
Acids and Bases
There are many ways to define an acid. For example, Arrhenius would define the acid as any species that increases the concentration of H+Â in an aqueous solution.
On the other hand, an Arrhenius base is any species that increases the concentration of OH− in an aqueous solution.
In an acid-base reaction, what we call the Neutralization reaction, an Arrhenius acid and base usually react to form water and a salt.
We measure the acidic or the basic character of a substance by measuring the concentration of H+ ions. The greater this concentration, the greater is the acidic character. The solution of a strong base with water is what we call an alkaline solution. Sodium Hydroxide or NaOH is an example of a strong base and HCl or Hydrochloric Acid is an example of a strong acid.
Solved Examples
Q 1:Â The chemical that we use as a fixer in photography is ……..
A) sodium thiosulphate       B) sodium sulphate
C) borax                    D) ammonium sulphate
Answer: During photography Na2S2O3xH2O or Sodium Thiosulphate functions as a fixer. So the answer here is A) sodium thiosulphate.
Q 2: Gunpowder is a mixture of which of the following chemicals:
A) potassium nitrate, powdered charcoal and sulphur.
B) aluminium nitrate, powdered charcoal and sulphur.
C) silver nitrate, powdered charcoal and sulphur
D) Powdered charcoal and TNT.
Answer: The correct option to select is A) potassium nitrate, powdered charcoal and sulphur.
Q 3:Â The hottest part of the flame is ………………
A) blue zone             B) dark zone
C) non-luminous zone    D) luminous zone
Answer: The correct option to select is C) non-luminous zone.
Q 4: Out of the following, ………….. is an inert gas.
A) Helium           B) Fluorine           C) Hydrogen         D) Nitrogen
Answer: The correct answer is A) Helium which is the first element of the Noble gases.
Q 5: Alloys are ……………
A) mixtures of two given non-metals in a fixed proportion.
B) Chemically inert substances that are metallic in character.
C) Purest forms of metals
D) mixtures of two or more metals in a known way.
Answer: The correct option is D) mixtures of two or more metals in a known way.
Practice Questions
Q 1: Out of the following elements, ……. is a liquid:
A) Helium           B) Bromine         C) Xenon         D) Radon
Ans: B) Bromine.
Q 2: The atomic number of an element is:
A) The number of electrons that an atom has.
B) This is the number of neutrons that an atom has.
C) It is the number of protons of that element.
D) It is the number of the position that an element occupies in any periodic table.
Ans:Â C) It is the number of protons of that element.
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