Only a few elements from the periodic table are present in the organic compounds.

Recalling from your memory, create a list of elements present in the first and second periods of the periodic table and place them in their respective positions. Many metals and metalloids are also part of organometallic compounds. Place Na, K, Mg, Al, and Si in your periodic table.

Elements under the same group in the periodic table exhibit the same chemical properties and reactivity. Explain why.

How many protons and electrons do the following species have?

a. K⁺

b. Ne

c. O^2–

What is the most likely charge to result from the ionization of Sr?

Determine the number of electrons calcium needs to gain or lose to achieve the noble gas configuration and identify which noble gas it represents.

Illustrate the given orbitals:

(i) 2s

(ii) 3s

(iii) 2p

True or false: He₂²⁺ does not exist.

Determine which of the following bonds will be longer and which will be stronger.

• C—Cl or C—I

Explain why the S−H bond in ethanethiol is longer than the O−H bond in ethanol if the S and O in the mentioned compounds are both sp³ hybridized.

Consider the structure shown below where only the σ bond is shown. Draw the missing π bonds and specify the orientation of the p orbitals used.

Add all the missing lone pairs in the structure below:

Shown below is the line-angle structure of (S)-malate. Draw all lone pairs of electrons. 

Using the periodic table, determine the position of each pair of specified atoms.

 1. Determine the total number of valence electrons for each element.

 2. Provide the total number of core electrons for each element.

a. Sodium and potassium

b. Boron and aluminium

What is the formal charge of the highlighted atom?