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प्रश्न
Define the following term with an example.
Metalloid
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उत्तर
Metalloid: Metalloid is a chemical element that exhibits some properties of metals and some of non-metals. Metalloids are generally semi-conductors.
Ex.: Silicon. Arsenic, Antimony and Boron.
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संबंधित प्रश्न
If bromine atom is available in the form of, say, two isotopes `""_35^79Br (49.7%)" and """_35^81Br (50.3%)`, calculate the average atomic mass of bromine atom.
The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes `""_8^16X" and """_8^18X` in the sample?
Tick the most appropriate answer.
Who discovered that radioactive rays are given out by uranium?
- Henri Becquerel
- Marie Curie
- Pierre Curie
- Schmidt
ANSWER IN DETAIL
State the postulates of the Dalton’s atomic theory.
Fill in the blank
An ion with positive charge is called ______
Define: Chemical bond
Give the charge and the mass of an electron, proton and neutron present in an atom ?
An atom has 13 protons and 14 neutrons.
What is the atomic mass of the atom ?
A certain particle ‘X’ has 17 protons, 18 electrons and 20 neutrons.
What is the atomic numebr of X ?
A certain particle ‘X’ has 17 protons, 18 electrons and 20 neutrons.
What is the charge on the particle ?
Fill in the blank
A charged particle is called an _____
Name the three subatomic particles present in an atom.
Why is it not possible to see an atom even with the most powerful microscope ?
What value has been given to the mass of this reference atom ?
What is an atom ? How do atoms usually exist ?
The electronic configuration of an element Z is 2, 8, 8.
(a) What is the atomic number of the element?
(b) State whether element Z is a metal or a non-metal.
(c) What type of ion (if any) will be formed by an atom of element Z? Why?
(d) What is special about the outermost electron shell of the atom of this element?
(e) Give the name and symbol of element Z.
(f) Name the group of elements to which Z belongs.
Electron, proton, neutron are the types of ______ in an atom.
Name the gas that.
Turns moist starch iodide paper blue black.
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
Which element will lose electron?
The electronic structure [configuration] of fluorine can be written as 2, 7. In a similar way give the electronic configuration of aluminium
Rewrite the given sentence in correct form.
Elements contain two or more kind of atoms and compounds contain only one kind of atom.
State true or false. If false, correct the statement.
The basic unit of an element is molecule.
State true or false. If false, correct the statement.
An atom is electrically neutral.
Project.
To have an idea of what atoms are, students can be asked to construct atoms using pipe cleaners (thin metal wires-electron shells), pompoms (balls-different colours for protons and neutrons) and beads (electrons). Students will love and enjoy putting them together and they look great hanging from the ceiling in the classroom.
Dalton’s atomic theory successfully explained
(i) Law of conservation of mass
(ii) Law of constant composition
(iii) Law of radioactivity
(iv) Law of multiple proportions
Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order
- Rutherford’s atomic model
- Thomson’s atomic model
- Bohr’s atomic model
Lead is also known as plumbum.
What is the fundamental particle of an element?
The first scientific theory about atoms was given by J J. Thomson.
