The electron configuration for Helium (He) is shown below. 152
Which diagram shows the correct distribution of electrons in the electron shells of a helium atom?
1P
ON

2 electrons in the atomic shell

Helium belongs to the noble gas group (group 18), s block and period 1

Electron configuration: 1s²

Symbol: ₂He⁴

With atomic number 2 and mass number 4, the composition of the subatomic particles is:

2 protons, 2 electrons, and 2 neutrons

2 protons and 2 neutrons make up the atomic nucleus while 2 electrons are in the atomic shell

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6