Physical Science Grade Course Describe the Difference

Physical Science

Grade Course

Describe the difference between a mixture and a compound

For basic understanding, a mixture comprises of two or more different substances which are not chemically combined to each other. On the other hand, a compound consists two or more chemically bonded different substances which are present in a fixed ratio. In other words, the difference between a mixture and a compound is evident from the mentioned definitions.

Furthermore, there are a number of ways in which a mixture and a compound differs. For example, compounds always contain elements in a fixed ratio. For this reason, Calcium Carbonate, a compound, would always contain 40% Calcium, 12% Carbon and 48% Oxygen by mass. No variations in the mass of these elements would be noticed in Calcium Carbonate. In contrast, a mixture would contain its substances in any proportion (example: salt and water). For this reason, a mixture can be separated into the components which it is made up of through distillation or dissolving unlike compounds which requires a chemical reaction to split it into different elements. This is merely because of the reason that whenever a compound is formed, a chemical reaction occurs and heat is either absorbed in or given out. However, in the case of the formation of a mixture, no chemical reaction takes place. Another conspicuous difference between the two is the fact that a mixture usually behaves in a similar manner as of its components whereas compounds always have a new set of characteristics which are not similar to the elements which they are made up of (Ramsden E, 2001).

- Suppose that you have a pure substance. How can you tell whether it is a compound or an element?

Since matter can be divided into pure substances and mixtures, a pure substance can either be an element or a compound. Given a pure substance, if asked to figure out whether it is an element or a compound, one requires to use various chemical techniques such as electrolysis, heating cooling and more. Upon using such techniques, if the pure substance breaks down into two or more elements than it is a compound. However, if the use of the chemical technique does not break down the pure substance and it remains the same with the changes in its state, than it would be an element. For instance, heating a copper piece would only melt it. The atoms would remain unaffected in whichever state they are.

What is the difference between an ionic and a covalent bond?

An ionic bond is a chemical bond which is formed through an electrostatic force of attraction between oppositely charged particles. Such bonds are usually formed between a positively charged particle (cation) which is usually a metal and a negatively charged particle (anion) which is usually a non-metal. The bond is formed when the metal looses electrons thereby having a positive charge and the non-metal gains electrons and becomes negatively charged. In other words, the loss and the gain of electrons make these atoms become charged particles (ions). In contrast, covalent bond is a type of a bond which is formed between two non-metals. Unlike the loss and the gain of electrons in the ionic bond, electrons are shared in a covalent bond. This gives the atom a full outer energy level (Pommerville J, 2010).

Explain why ionic compounds are formed when a metal from the left side of the periodic table reacts with a nonmetal from the right side. Give two examples of such compounds

The basic idea when atoms bond to each other is the fact that every atom wants to have an electronic configuration like the noble gases. These noble gases have full or a complete outermost electron shell. Therefore, in order to obtain a complete outermost shell, the electrons either lose their one or two electrons which are present in the valence shell or gain them when they are require one or two electrons to achieve the electronic configuration similar to the noble gases. For this reason, the metals present at the left side of the periodic table belong to group one and group two have one or two electrons in their outermost shell which they tend to lose. On the other hand, the non-metals present on the right side of the periodic table usually belonging to the sixteenth and the seventeenth group have six or seven valence electrons and therefore want to gain the remaining one or two electrons in order to achieve the state of noble gases. In this way, upon losing the valence electrons, the metals at the left side of the periodic table become cations and upon gaining one or two electrons, the non-metals at the right of the periodic table become anions. These cations and anions through electrostatic forces of attraction form an ionic bond. Some of the examples of such bonds include Sodium Chloride (NaCl). The electronic configuration of Sodium can be written down as 2, 8, 1 showing that it has to lose one electron in order to become stable. Similarly, the electronic configuration of chlorine is 2, 8, 7 depicting that it requires one electron to achieve the configuration of the noble gas. Hence, upon losing one electron, Sodium becomes positively charged and this electron is gained by Chlorine which becomes a chloride ion (negatively charged) (Pommerville J, 2010).Sodium and Chloride ions are held strongly be electrostatic forces of attraction thereby forming an ionic bond. Another example of an ionic bond is Magnesium Oxide (MgO). The electronic configuration of Magnesium is 2,8,2 showing that it should lose 2 electrons in order to become stable. The electronic configuration of Oxygen is 2, 8, 6 which shows that upon receiving two electrons, it would achieve the stability like the noble gases. Therefore, the 2 electrons are given by Magnesium which is gained by Oxygen. In this way, they become charged particles and are held in strong ionic bond through electrostatic forces of attraction.