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Question
Is it possible to see atoms these days ? Explain your answer.
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Solution
Yes, it is possible to see atoms these days, with the help of advanced technology. Electronic microscopes are extremely powerful and can magnify even the smallest particle. A Scanning Tunnelling Microscope (STM) can be used to produce highly magnified images of the surface of elements on a computer screen. Therefore, a highly sophisticated STM can be used to view atoms indirectly.
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ANSWER IN DETAIL
State the postulates of the Dalton’s atomic theory.
Define: Relative atomic mass
Name the particles which revolve around the nucleus.
An atom of an element X may be written as `""_9^4"X"`
(a) What does the figure 9 indicate?
(b) What does the figure 4 indicate?
(c) What is the number of protons in atom X?
(d) What is the number of neutrons in atom X?
(e) What is the number of electrons in atom X?
(f) How many electrons are there in the outermost shell of an atom of element X?
(g) Write the symbol of ion formed by an atom of element X.
Find the mass of 2 moles of nitrogen atoms.
Draw the diagrams representing the atomic structures of the following: Neon
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
Which will form negative ion?
Draw the basic structure of an atom representing its –
- Subatomic particles
- Nucleus
- Orbits or shells.
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.
Define the following term with an example.
Compound
Which of the following statements made by Dalton has not undergone any change?
In the nucleus of `""_20"Ca"^40`, there are ______
The number of atoms present in a molecule is called its ______.
1 mole of Gold and Silver contain same number of atoms.
