Question

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for parts of the free - response question early show the method used and the
steps involved in arriving at your answers. you must show your work to receive credit for your answer.
examples and equations may be included in your answers where appropriate.

answer the following questions related to the chemical bonding in substances containing cl.

(a) what type of chemical bond is present in the cl₂ molecule?

note on your ap exam, you will handwrite your responses to free - response questions in a test
booklet

(b) cl₂ reacts with the element sr to form an ionic compound. based on periodic properties, identify a
molecule, x₂ that is likely to react with sr in a way similar to how cl₂ reacts with sr. justify your
choice.

Explanation:

Part (a)

In a $\ce{Cl_{2}}$ molecule, both atoms are chlorine (non - metals). A covalent bond is formed when two non - metal atoms share electrons. Since the two $\ce{Cl}$ atoms have the same electronegativity, they share a pair of electrons equally, so the bond is a non - polar covalent bond.

1. Identify the group of Cl: Chlorine ($\ce{Cl}$) is in Group 17 (halogens) of the periodic table. Elements in the same group have similar chemical properties because they have the same number of valence electrons.
2. Choose a similar element: Bromine ($\ce{Br}$) or iodine ($\ce{I}$) or fluorine ($\ce{F}$) are also in Group 17. Let's take $\ce{Br_{2}}$ as an example. $\ce{Sr}$ is an alkaline earth metal (Group 2). Alkaline earth metals react with halogens to form ionic compounds. $\ce{Cl_{2}}$ reacts with $\ce{Sr}$ to form $\ce{SrCl_{2}}$ (an ionic compound) because $\ce{Sr}$ loses 2 electrons (to achieve a stable octet) and each $\ce{Cl}$ atom gains 1 electron. $\ce{Br}$ is in the same group as $\ce{Cl}$, so $\ce{Br_{2}}$ has similar chemical reactivity. $\ce{Sr}$ will lose 2 electrons and each $\ce{Br}$ atom will gain 1 electron, forming $\ce{SrBr_{2}}$, which is an ionic compound, just like the reaction between $\ce{Cl_{2}}$ and $\ce{Sr}$.

Answer:

The type of chemical bond present in the $\ce{Cl_{2}}$ molecule is a non - polar covalent bond (or covalent bond).

Part (b)