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प्रश्न
Define the following term:
Atom
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उत्तर
An atom is the smallest particle of an element which retains its chemical identity in all physical and chemical changes.
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.
MATCH THE COLUMNAS
| 1. Jpham Dalton | a. Neutrons |
| 2. Atom | b. Model of the atom |
| 3. Chadwick | c.The atomic theory of matter |
| 4. Rutherfrod | d. Positively charged |
| 5. Protons | e. Electricity neutral |
| 6. Nuclear fusion | f. Generator of electricity |
| 7.Gamma -rays | g. High penetrating power |
| h.Energy in sun |
TRUE \ FALSE
Elements combine in definite proportions to form compounds.
WRITE SHORT ANSWER
Define an ionic compound.
ANSWER IN DETAIL
State the postulates of the Dalton’s atomic theory.
ANSWER IN DETAIL
Enlist the features of Bohr’s model of an atom. How did he correct the Rutherford’s model ?
Write the names of `"Na"_3"PO"_4` compounds :
Fill in the blank
An ion with negative charge is called _______
Define: Mass number
A certain particle ‘X’ has 17 protons, 18 electrons and 20 neutrons.
What is the atomic numebr of X ?
Fill in the blank
If an atom gains an electron, it is called an _______
How is the size of an atom indicated ?
State two observations which show that atom is not indivisible.
What is an atom ? How do atoms usually exist ?
Calculate the number of moles in 12.044 × 1025 atoms of phosphorus.
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
What will be the charge present of the molecule XY after chemical combination?
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.
An element is composed of ______ atoms.
In the nucleus of `""_20"Ca"^40`, there are ______
The smallest unit of an element is ______.
