Chemical Bonds in Compounds Name:_______________________ When a compound such as salt, sugar, copper sulfate, or glucose are formed, the elements in each compound are held together by what are called chemical bonds. A chemical bond is a force of attraction between two atoms. Recall that electrons are the negatively charged part of an atom that move around the nucleus. Atoms are able to transfer (give) or share electrons between each other and those chemical bonds cause an attraction. Recall that electrons move around the nucleus of an atom. This outer “cloud” of the atom has layers and there are only a certain number of electrons that can fit in each layer. The first layer can hold two electrons, the second layer can hold eight electrons, the third can hold eighteen electrons, and so on. These atoms naturally want to have full cloud layers. When atoms that are lacking electrons come into contact with other atoms, they naturally want to give or gain electrons to balance out. A type of bond where an atom gives, or transfers, one or more electrons to another atom is called an ionic bond. When an atom has the same number of protons (positive charge) and electrons (negative charge), the atom remains neutral (no charge). However, once an atom loses one or more electrons (the negative charge), the atom itself becomes positively charged. An atom with a charge is called an ion. Ions do not have the same number of electrons as they do protons. The atom that loses an electron is called a positive ion and the atom that receives the extra electron now has a negative charge and is called a negative ion. These two ions attract each other because opposite forces (positive and negative) attract and form a bond. This is how compounds are created. Another way elements are bonded together is through a covalent bond. Covalent bonds SHARE electrons rather than giving them away or taking them. Electrons are always shared in pairs. A good example of a covalent bond is water (H2O). The electrons (negative charges) from two hydrogen atoms and the electrons from one oxygen atom are attracted to the positive charges held in the nuclei of each other. This attraction allows the atoms to be held together to form a compound (water).

In the world around us, there are millions of chemical compounds In the world around us, there are millions of chemical compounds. Scientists like to classify (organize into groups based on similar properties) chemical compounds into two groups based on their bond type: ionic compounds and covalent compounds. As the names suggest, ionic compounds are the compounds formed with ionic bonds and covalent compounds are compounds formed with covalent bonds. Ionic compounds (such as sodium chloride, or table salt) tend to be brittle, have a high melting point, be arranged in a crystalline pattern, and are in a solid state in room temperature. Many of them can be dissolved in water. Covalent compounds (such as water and wax) often have a lower melting point and many are not water soluble (although some, like sugar, are an exception). Under the terms “Ionic” and “Covalent”, explain what each of them are. Next, using the atom diagrams on the left, create a visual of each type of bond. Ionic Covalent How do chemical bonds create substances such as water, salt, and sugar? Use information in the reading prompt to support your answer. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________