GRADE 11 DATE: 23 April 23, 2022 SESSION 6 CHEMISTRY Matter and Material NOTES A Chemical bonds is a mutual attraction between two atoms resulting from the simultaneous attraction between their nuclei and the outer electrons. - In simple terms we can say is the bond that hold atoms together into molecules. - We have difference kinds of chemical bonds, but we have primarily three types of bonds ◼ Ionic Bonding A common example is Sodium Chloride (NaCl) ◼ Covalent bonding A common example is water molecule (𝐻2 𝑂) ◼ Metallic bonding – it is self-explanatory, it is a bond between metal elements. However, in grade 10 you already did Metallic and Ionic bonds thoroughly, if you forgotten them, I suggest you revise them. Molecular structure Important terminologies 1. Electronegativity – Is a measure of the tendency of an atom in a molecule to attract bonding electrons. 2. Bond polarity – Is the separation of electric charge from a bond, leading to a molecule or its chemical group having an electric dipole or dipole moment. (This is because electrons are not always shared equally among two atoms or bonded atoms. 3. Bond energy – (of a compound) is the energy needed to break one mole if its molecules into separate atoms. 4. Bond length – Is the average distance between the nuclei of two bonded atoms. 5. Valence electron – are the electrons in the highest energy level of an atom in which there are electrons. i.e., Outer electrons Lewis dot diagram is a structural formula in which valence electrons are represented by dot or crosses. It is also known as an electron dot formula, a Lewis formula, or an electron diagram. Look at the following examples of Lewis diagram. Oxygen ion Cobalt Oxide NOTE: Atoms usually share electrons in a way that allows them to satisfy the OCTET RULE. Practice Questions: 1. How many valence electrons do group 17 element possess? 2. What is the difference between electron Shell and Electron Orbit? 3. How does the number of valence electrons change as one move from left to right on of the periodic table? Answers: 2. Electron Shell –is a way of grouping electrons surrounding the nucleus of an atom. Electron orbit – Is one the path of an electron around the nucleus of an atom. For more of the information analyze the following illustrations. Electron Orbits – shows us the level of electron movements from level s to p, for our level of educations. Electrons Shells – always surround an atom to show all electrons that make up that atom. Along site we have Carbon Atom. You will do more questions in class.