Little is known about the properties of astatine, At, because of its rarity and high radioactivity. Nevertheless, it is possible for us to make many predictions about its properties. (c) What is the chemical formula of the compound it forms with Na?

Verified step by step guidance

1. Identify the position of astatine (At) in the periodic table. Astatine is a halogen, found in Group 17.
2. Recognize the typical valence of halogens. Halogens generally have a valence of -1 when forming compounds.
3. Identify the position and typical valence of sodium (Na). Sodium is an alkali metal in Group 1 and typically has a valence of +1.
4. Combine the valences of sodium and astatine to predict the formula of the compound. Since sodium has a +1 charge and astatine has a -1 charge, they can combine in a 1:1 ratio.
5. Write the chemical formula using the symbols for sodium and astatine, ensuring the total charge is neutral. The formula is NaAt.

Key Concepts

Chemical Bonding

Chemical bonding refers to the forces that hold atoms together in compounds. In the case of astatine (At) and sodium (Na), the bond formed is ionic, where sodium donates an electron to astatine, resulting in the formation of Na+ and At- ions. Understanding this concept is crucial for predicting the formula of the compound formed.

Ionic Compounds

Ionic compounds are formed when metals and nonmetals react, resulting in the transfer of electrons. Sodium, a metal, loses one electron to become Na+, while astatine, a nonmetal, gains an electron to become At-. The resulting compound is electrically neutral, and its formula reflects the ratio of the ions involved.

Chemical Formulas

A chemical formula represents the elements in a compound and their respective ratios. For the compound formed between sodium and astatine, the formula is NaAt, indicating one sodium ion for every astatine ion. This notation is essential for conveying the composition of the compound succinctly.