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Chemistry - Unit 01

QuestionAnswer
What are matter/substances? Those that have mass and occupy space.
What is Atom? Basic building unit of matter.
Who discovered electron? JJ.Thomson
How was electrons discovered? JJ.Thomson was conducting an experiment on the conduction of electricity through gases under low pressure and discovered a type of negatively charged particles. The particles were identified as electrons.
When the electrons was found, what was the conclusion thy came onto? It was disclosed that atoms are made up of sub atomic particles and that electron is one such sub atomic particle.
To what conclusion did they come unto when they discovered electrons as negatively charged particles? It was opined that within the atom there should also be positively charged particles neutralizing the negative charge created by electrons.
Who discovered the existence of positively charge particles in atoms? Goldstein, a German scientist.
The mass of the +charged particle was found to be? Equal to the mass of a hydrogen atom.
Who named the + charged particles as protons? Ernest Rutherford, a New Zealand born scientist.
After the discovery of protons and electrons, what wa the problem they foresaw? Since the + and - particles attract each other, how they pack in an atom became a problem.
Who proposed the plum pudding model? J.J. Thomson.
How did J.J. Thomson explain, according to the plum pudding model? An atom is a solid sphere with smeared out +charge. Electrons are embedded in it in different places like the plums in an apple pudding. The atom is electrically neutral because the + & - charges are equal.
Why was the plum pudding model later rejected? It did not explain how the attraction between unshileded protons and neutrons is nullified.
Who discovered the existence of neutrons in atoms? James Chadwick, in 1932.
The mass of the neutron was? Nearly equal to the mass of a proton.
What was the name of the apparatus through which electrons was first found? Cathode Ray Apparatus
Who proposed the planetary model? Ernest Rutherford, a New Zealand born scientist.
How was the planetary model explained? It was stated that the nucleus of an atom is made up of protons and neutrons and the electrons revolve around the nucleus like how the planets orbit around the sun. These orbits were called shells.
What are nucleons? The particles, protons and neutrons which constitute the nucleus are collectively called nucleons.
Explain the atomic model accepted at present The electrons are located at a certain distance from the nucleus in relation to their energy. So, electrons in atoms lie in different energy levels. There is a maximum number of electrons that can be occupied in a given energy level.
What is the maximum number of electrons that can exist in the last energy level of a free atom? 8
State the max number of electrons allowed for the following energy levels: 1, 2, 3, 4. 1(K) - 2. 2(L) - 8. 3(M) - 18. 4(N) - 32.
What is the atomic number? The no. of protons in an atom of a given element is called the atomic number of that element.
What is the symbol of atomic number? Z
What is atomic mass number? The sum of the number of protons and the number of neutrons contained in the nucleus of an atom is called the atomic mass number.
What is the symbol of atomic mass number? A
State an equation for finding the mass number of an atom. Mass no equals the No of protons + No of neutrons
Show the standard symbol of indicating atomic number and mass number AZM
What are isotopes? The atoms of the same element with different mass numbers are known as isotopes (different number of neutrons)
Hydrogen has 3 isotopes, with the atomic mass number as 1, 2, 3. Name these isotopes. 1 - Protium. 2 - Deuterium. 3 - Tritium
What is the most abundant isotope of the 3 H isotopes? Protium.
What do you mean by the electronic configuration? The distribution of electrons in the respective energy levels of an atom from the innermost level to the outermost level is known as the lectronic configuration.
What are noble gases? gg
Give 3 examples of noble gases. He, Ne, Ar.
What is the atomic mass unit? The unit used to express the masses of atoms is the atomic mass unit.
What is the relative atomic mass? The comparison value of the atomic mass with 1/12 mass of isotope 12 C
Formula for the Relative atomic mass of an element? RAM equals the Mass of an atom of the element / mass of 12 6C atom x 1/2
What is the smallest particle of an element that takes part in a chemical reaction? Atom
How are chemical compounds formed? They are formed by the chemical combination of two or more elements.
What do you mean by chemical bonds? The attractive forces created among the atoms when electrons are rearranged are called chemical bonds.
What are ionic bonds? Bonds formed by th removal or receiving of electrons is known as ionic bonds.
Provide 7 examples of ionic compounds. MgCl2, CaO, NaOH, NaCl, CaCl2, MgO, NaO
Give another name for ionic bonds Electrovalent bonds.
What do you mean by a giant ionic lattice? In a ionic bond, attractive forces are created among the + & - ions and therefore they are organized into a regular array and placed in definite positions. This arrangement is called a giant ionic lattice.
State some properties of ionic compounds.(5) gg
Why can the ionic compounds only conduct electricity in the solution and the fused states and not in solid state? It is the presence of mobile ions that can conduct electricity both in the solution and the fused state. After the breaking down of the lattice in the liquid or aqueous state, the ions become mobile.
What are covalent bonds? If one or many pairs of electrons in the outermost energy level are shared between two atoms of the same element or different elements the bonds are called covalent bonds.
Sharing of electrons among the atoms of the same element form? Homoatomic molecules of those elements.
Sharing of electrons among the atoms of the different elements form? Heteroatomic molecules of compounds.
Provide 7 examples of covalent compounds. CH4 (methane), NH3 (Ammonia gas), C2H5OH (Ethyl alcohol), CO2 (Carbondioxide), C6H12O6 (Glucose), Sulphurdioxide (SO2)
State some properties of covalent compounds.(3) gg
What are the names of the 2 American scientists who put forwars the Lewis Structure? Gilbert Lewis & Erwin Langmuir, in 1916.
What was the view put forward by the Lewis structure? That the chemical bonds are always formed amond the electrons in the outermost energy levels. These electrons are also called valency electrons.
What is Valency? Valency is the combining power or combining capacity of an element.
The valency of an element is equal to? The no. of electrons removed or accepted by an atom of that element or the number of pairs of electrons shared between the atoms if those elements.
Created by: Jaydin