Valence Electrons and Periodic Trends

The video tutorial covers valence electrons, their role in chemical bonding, and how they differ from core electrons. It explains the valence electron configurations for main group elements and transition metals, using examples like boron, sodium, and tin. The tutorial also discusses the periodicity of chemical properties and provides exercises to practice determining electron configurations.

What are valence electrons primarily responsible for?

• Magnetic properties

• Chemical bonding and reactions

• Nuclear reactions

• Gravitational forces

Which of the following elements has three valence electrons?

• Sodium

• Calcium

• Aluminium

• Tin

In the periodic table, what does the column number of main group elements indicate?

• The number of protons

• The number of neutrons

• The number of valence electrons

• The atomic mass

For transition metals, which electrons are considered valence electrons?

• Only the outermost s electrons

• All electrons in the atom

• Outermost s electrons and all electrons in partially filled sublevels

• Only the d electrons

What is the valence electron configuration for nickel?

• 4s2 3d8

• 4s1 3d9

• 3s2 3p6

• 5s2 4d8

Which element has a valence electron configuration of 6s2 5d4?

• Selenium

• Europium

• Tungsten

• Cadmium

How many valence electrons does selenium have?

• Five

• Six

• Four

• Seven

What is the full electron configuration for titanium?

• 1s2 2s2 2p6 3s2 3p6 4s2 4d2

• 1s2 2s2 2p6 3s2 3p6 4s2 3d2

• 1s2 2s2 2p6 3s2 3p6 3d2 4s2

• 1s2 2s2 2p6 3s2 3p6 3d4

Which element typically has a +3 charge due to its valence electrons?

• Magnesium

• Iodine

• Sodium

• Aluminium

What causes the gradual change in chemical properties across a period in the periodic table?

• Changes in the number of neutrons

• Changes in the number of valence electrons

• Changes in the number of protons

• Changes in atomic mass