Understanding Electron Configurations and Reactivity

The video tutorial explains the concept of valence and core electrons, focusing on how electron configurations can predict an element's reactivity. It uses oxygen and calcium as examples to illustrate how valence electrons influence chemical reactions. The tutorial also discusses the stability of noble gases due to their full electron shells and how elements like calcium achieve stability by losing electrons.

What is the main purpose of understanding electron configurations?

• To determine the color of an element

• To predict how an element will react with others

• To find the temperature at which an element melts

• To calculate the weight of an atom

How many valence electrons does a neutral oxygen atom have?

• Two

• Four

• Six

• Eight

What is the electron configuration of a neutral oxygen atom?

• 1s2 2s2 3p4

• 1s2 2p6 3s2

• 1s2 2s2 2p6

• 1s2 2s2 2p4

Why is it beneficial for oxygen to gain two more electrons?

• To become a noble gas

• To fill its outer shell and become more stable

• To change its color

• To increase its atomic number

What is the electron configuration of calcium in noble gas notation?

• [Kr] 5s2

• [He] 2s2 2p6

• [Ar] 4s2

• [Ne] 3s2 3p6 4s2

How does calcium achieve a stable electron configuration?

• By losing six electrons

• By gaining six electrons

• By losing two electrons

• By gaining two electrons

How many core electrons does a neutral calcium atom have?

• Twenty

• Eight

• Eighteen

• Two

Which of the following elements is likely to lose electrons to achieve stability?

• Oxygen

• Calcium

• Neon

• Helium

Which column in the periodic table has elements with one valence electron?

• First column

• Second column

• Fourth column

• Third column

What makes noble gases very stable?

• They have a high atomic mass

• They have a filled outer shell

• They have a low melting point

• They are highly reactive