crexam Questions la Sulfur and oxygen are both in group 6 of the periodic table. Explain, in terms of their electronic configurations why they are both in group 6. (2) An atom of phosphorus contains 15 electrons. Describe how these 15 electrons are arranged in a phosphorus atom. (2) Phosphorus oxide is a compound that contains covalent bonds. Describe what is meant by a covalent bond. (2) (A) Tetrachloromethane is a simple molecular, covalent compound. The formula of its molecule is CCl_(4) There are four electrons in the outer shell of a carbon atom. There are seven electrons in the outer shell of a chlorine atom. Draw a dot and cross diagram to show the bonding in a molecule of tetrachloromethane, CCl_(4) Show outer shell electrons only. 3)Sodium fluoride is an ionic compound. Describe how a sodium atom and a fluorine atom interact to form a sodium ion, Na^+ and a fluoride ion, F.

## Step1: Group 6 Elements### Sulfur and oxygen are both in group 6 of the periodic table because they each have 6 electrons in their outermost electron shell. This is a characteristic of all group 6 elements.## Step2: Electron Configuration of Phosphorus### An atom of phosphorus contains 15 electrons. These electrons are arranged in the electron configuration of . This means that phosphorus has two electrons in the first shell, eight in the second shell, and five in the third shell.## Step3: Covalent Bond Definition### A covalent bond is a type of chemical bond where two atoms share one or more pairs of valence electrons. This sharing allows each atom to attain the electron configuration of a noble gas, achieving stability.## Step4: Dot and Cross Diagram for ### In a molecule of tetrachloromethane ( ), the carbon atom shares its four outer shell electrons with four chlorine atoms, each of which shares one of its seven outer shell electrons with the carbon atom. The dot and cross diagram will show the carbon atom in the center with four pairs of shared electrons (one pair with each chlorine atom). ## Step5: Formation of Sodium Ion and Fluoride Ion### A sodium atom ( ) has one electron in its outer shell, while a fluorine atom ( ) has seven electrons in its outer shell. To achieve a stable electron configuration, the sodium atom donates its one outer electron to the fluorine atom. This results in the formation of a sodium ion ( ), which has a positive charge due to the loss of one electron, and a fluoride ion ( ), which has a negative charge due to the gain of one electron.