Assignment 3: Mixtures, Compounds, Elements, Ionic and Covalent Bonds
By: Karen Owens
November 17, 2012
SCI 110
Professor Lawrance Mullen

1. Describe the difference between a mixture and a compound.
The difference between a mixture and a compound is that a mixture is a substance made by mixing other substances together. Most of the time two or more substances that are chemically united and they do not exist in fixed proportions of each other. Unlike a compound a mixture can be physically separated into pure compounds or elements. For example a cake is made up of different substances that are mixed together that are separated.
A compound on the other hand is just the opposite of a mixture. A compound has a constant composition with fixed ratio of elements. It can have properties different from its constituents as a new substance is formed when they are chemically combined. The difference is that a compound can only be separated by chemical methods. That is like taking platinum and gold and melting them both down together. You get platinum gold which is a mixture of two elements combined together. 2. Suppose that you have a pure substance. How can you tell whether it is a compound or an element?
You can tell the difference because a compound is a mixture of two or more elements. An element on the other hand is a single thing. It is actually divided into pure substances and mixtures. When we have two or more things that are not chemically combined that is called a mixture. They can be divided into homogeneous, like the particles that are throughout milk or heterogeneous, in which we can tell it is mixed like sand and salt.
A pure substance on the other hand is when something is chemically combined and can be divided into compounds made up of elements, like water (H2O). For elements we have basic substances that are used, for example gold which is Au on the periodic table. Therefore in order to tell if a pure substance is a compound or element, you simply need to know if whether the substance is the element, made up of two or more different elements that can be observed by seeing the formula. The other option is to know if the substance is a compound by testing the thing and seeing what elements make up the item. 3. What is the difference between an ionic and covalent bond?
In order to know the difference between an ionic and covalent bond, we have to first understand the meaning of both bonds. Although they are somewhat similar in what they mean, they also differ. An ionic bond is a chemical link between two atoms caused by the electrostatic force between oppositely-charged ions in an ionic compound. A covalent bond Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together (Tillery, 2009).
The difference between an ionic and covalent bond are that an ionic bond is formed between two atoms. This is usually done by a metal and non-metal loosing or gaining an electron. The ionic bond makes ions that are atoms charged because they either gain or lose an electron. These ions have a positive for the metals and a negative for the non-metals charge. The opposites attract to each other and form an ionic bond. For example, a car battery has a negative and positive side. If the charges for both go on the wrong way, the car will not start.
Covalent bonds on the other hand are usually between two non-metals. They involve atoms that share electrons and they do not lose or gain electrons. This type of bond will share atoms to gain full outer energy levels. By sharing these electrons the atoms form a bond known as the covalent bonds. For example if you dip an iron nail into cooper, you will get a cooper plated nail. 4. 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.

5. Explain why covalent bonds are formed when nonmetals from the right side of the periodic table bond with each other. Give two examples of such compounds.