Electron Configuration of the First 20 Elements

The video tutorial explains the atomic structure, focusing on atomic number and mass, and how they relate to protons, neutrons, and electrons. It introduces electron shells and configurations, particularly for the first 20 elements, and discusses how these relate to the periodic table's group and period numbers. The tutorial includes exercises for drawing electron configurations and highlights trends in valence electrons. It concludes with a summary and a brief mention of more complex topics for future lessons.

What does the atomic number of an element represent?

• The atomic weight of the element

• The number of electron shells

• The number of protons in the nucleus

• The number of neutrons in the nucleus

How is the atomic mass of an element determined?

• By the number of electrons and neutrons

• By the number of protons and neutrons

• By the number of protons and electrons

• By the number of electron shells

How many electrons can the first electron shell hold?

• 18

• 10

• 8

• 2

Which electron shell does the third electron of a lithium atom occupy?

• Second shell

• Fourth shell

• Third shell

• First shell

What is the electron configuration of a helium atom?

• 1 electron in the first shell

• 2 electrons in the first shell

• 2 electrons in the second shell

• 1 electron in the second shell

How many electron shells do elements in the second period have?

• 1

• 2

• 3

• 4

What is the relationship between group number and valence electrons for elements in the second period?

• Group number equals the number of electron shells

• Group number equals the number of protons

• Group number equals the number of valence electrons

• Group number equals the atomic mass

How many electron shells do elements in the third period have?

• 1

• 4

• 2

• 3

Which electron shell do the valence electrons of potassium and calcium occupy?

• Third shell

• Fourth shell

• Second shell

• Fifth shell

What does the number of electron shells correspond to in the periodic table?

• Group number

• Period number

• Atomic number

• Atomic mass