Grade 8 Atomic Structure

The highest energy is in the ______________ circle of the atom.

• innermost

• outermost

• All the same

• No one knows!

Match the term to its modern meaning

• Parmanu: Atom

• Parmanu: Molecute

• Anu: Atom

• Anu: Molecute

Match the person to the period

• Maharishi Kanad - 5th Century BCE

• Democritus - 6th Century BCE

• Democritus - 5th Century BCE

• Maharishi Kanad - 6th Century BCE

Dalton's Atomic theory was proposed in 1808 by an English school teacher. Which of the following did he NOT say?

• All matter is made up of small particles called atoms.

• Atoms are indivisible (Burp!)

• Atoms cannot be created, destroyed, or changed.

• All atoms of a given element are alike (Ahem!)

• In a chemical reaction, atoms are divided.

Which of these is NOT a subatomic particle?

• Proton

• Electron

• Neutron

• Nucleons

• Ions

In 1897, JJ Thompson, a British scientist started working on cathode rays. Through his experiments, he discovered all of the following except:

• Cathode rays consist of negatively charged particles called electros, which are present in all atoms.

• Cathode Rays travel in straight lines

• Cathode rays consist of a stream of fast moving particles

• Cathodes attract positively charged particles.

• Cathode rays are made up of negatively charged particles (i.e., electrons)

Mark all properties of electrons that are true

• Electrons are the lightest subatomic particle with just 9.1 * 10 ^-28 grams of mass.

• They have a definite charge and a definite mass, irrespective of the element that they are a part of.

• They determine the Atomic number of an element.

• They determine the Atomic Mass of an element.

• An electron carries 1.602 *10 ^-19 Coloumb of negative charge. This is one unit negative charge.

Two of the following statements are true about this picture. Which two?

• This image indicates the experiment of Eugene Goldstein that led to the discovery of protons.

• This is the Cathode Ray experiment of JJ Thompson.

• The Cathode rays are deflecting towards the positively charged region. This proves that they are negatively charged.

• This experiment was conducted in 1902.

What is this an image of?

• Dalton's Atomic Model

• Thompson's Atomic Model

• Bohr's Atomic Model

• Rutherford's Atomic model

Kshama has matched the year to the discovery. But not all her points are correct. Which ones are incorrect?

• 1808 Dalton's Atomic Theory

• 1897 Rutherford's Gold foil experiment

• 1878 Thomson's Cathode Ray experiments

• 1886 Eugen Goldstein Discovery of protons

• 1878 Sir William Crookes Cathode Rays