REVIEW MATERIAL-E.Science 8- Q2

As scientists have learned more and more about atoms, the atomic model has also changed. Who among these scientists below proposed that electrons move around the nucleus in a specific layer like the planets orbiting around the sun?

• Ernest Rutherford

• John Dalton

• J.J. Thompson

• Niels Bohr

What do you call the atoms of the same element that have different numbers of neutrons in the nucleus and different mass numbers?

• Ions

• Isometrics

• Isopropyl

• Isotope

Some oxygen isotopes have 8 protons and 8 neutrons in their nucleus, which gives them an atomic number of ___________.

• 8

• 16

• 24

• 32

What do you call the arrangement of electrons in an atom’s orbitals, which is fundamental to understanding chemical properties and behavior of elements?

• Electron configuration

• Electron shells

• Hund’s rule

• Pauli’s exclusion

The first energy level has 1 sublevel “1s”. The second energy level has 2 sublevels “2s and 2p”. How many sublevels exist on the 3rd energy level?

• 3

• 4

• 5

• 6

The electron configuration of an element follows certain rules. One is that an orbital can only hold a maximum of two electrons with opposing spins. Which is being referred to by this rule?

• Extension rule

• Electron principles

• Hund’s rule

• Pauli Exclusion principle

In order to occupy the same orbital, two electrons must have _________.

• opposite spin

• opposite charge

• low energy

• the same direction of spin

What element has the electron configuration of 1s²2s²2p⁶3s²3p⁵ ?

• Bromine

• Chlorine

• Iron

• Phosphorus

Which in the examples is NOT a pure substance?

• Baking soda

• Diamond

• Sea water

• Table salt

Which one of the following statements about compounds is correct?

• At least one of the elements in a mixture must be a gas.

• The elements in a compound are always present in the same ratio.

• It is easy to separate a compound into the elements that is made from.

• The properties of a compound are the same as the properties of the elements which is made up