Chemical Bonding in Physical Science grade 11

GRADE 11 SENIOR HIGH SUBJECT

1. C H E M I C A L B O N D I N G Physical Science 11th Grade

2. 01 CHEMICAL BONDING

3. Matter are made up of atoms, but in most cases, those atoms aren’t just floating around individually. Instead, they’re usually interacting with other atoms or group of atoms.

4. What is chemical bonding? Chemical bonding refers to the formation of a chemical bond between two or more atoms, molecules or ions to give rise to a chemical compound. These chemical bonds are what keep the atoms together in the resulting compound.

5. For instance, atoms might be connected by strong bonds and organized into molecules. Or they might form temporary, weak bonds with other atoms that they bump into or brush up against.

6. When forces are attractive in nature, energy decreases. When the forces are repulsive in nature, the energy increases.

7. Why form chemical bonds? Atoms are trying to reach the most stable (lowest-energy) state that they can. Many atoms become stable when their valence shell is filled with electrons or when they satisfy the octet rule ( by having eight valence electron ).

8. 02 TYPES OF CHEMICAL BONDS

9. When substance participate in chemical bonding and yield compounds, the stability of the resulting compound will be determined by the type of chemical bonds it contains. The type of chemical bonds formed varies in strength and properties. These types of bonds in chemical bonding are formed from the loss, gain or sharing of electrons between two atoms/ molecules.

10. I. IONIC BONDING Ionic bonding is a type of chemical bonding which involves a transfer of electrons from one atom or molecule to another. Ionic bonding usually happens between metal and non-metal elements.

11. II. COVALENT BOND A covalent bond indicates the sharing of electrons between atoms. Compounds that contain carbon (organic compounds) commonly exhibit this type of chemical bonding. The pair of electrons which are shared by the two atoms now extend around the nuclei of atoms, leading to creation of a molecule. Usually happens between 2 non-metals.

12. A. Polar Covalent bond A polar covalent bond exists when atoms with different electronegativities share electrons in a covalent bond. The more electronegative atom pulls the electron pair closer to it self and away from the less electronegative atom.

13. B. Non- Polar Covalent bond A non-polar covalent bond is a type of chemical bond that is formed when electrons are shared equally between two atoms.

14. III. HYDROGEN BOND Hydrogen bonding is a weaker form of chemical bonding. It is a type of polar covalent bonding between oxygen and hydrogen, where in hydrogen develops a partial positive charge. This implies that the electrons are pulled closer to the more electronegative oxygen atom.

15. 03 LEWIS STRUCTURE

16. Lewis Structure A Lewis Structure is a very simplified representation of the valence shell electrons in a molecule . It is used to show how the electrons are arranged around individual atoms in a molecule. Electrons are shown as "dots" or for bonding electrons as a line between the two atoms. The goal is to obtain the "best" electron configuration, i.e. the octet rule and formal charges need to be satisfied.

17. How to draw Lewis Diagrams First determine the total number of valence electrons in the molecule.

18. Example: What is the Lewis dot structure of Chlorine? Chlorine is Cl which has 7 valence electrons. So the Lewis structure of chlorine can be written as: Cl

19. Lewis bonding are often used to represent covalent boding in molecules or ions. In covalent bonding atoms share valence electrons in order get full octet or duet (duet for H). Example of simplest molecule:   H H Note: 1 single line = 1 bond = 2 electrons 2 single lines = 2 bonds= 4 electrons 3 single lines = 3 bonds= 6 electrons

20. Example of molecule with double bond: Step 1: Determine the no. of valence electron O = 6 Step 2: Place the dots Step 3: use lines to show bonding   O O O O Lone pairs

21. Example of molecule with triple bond: Step 1: Determine the no. of valence electron N = 5 Step 2: Place the dots Step 3: use lines to show bonding   N N N N

22. Let’s try: Step 1: Count all the no. of valence electron H = 1 x 2= 2 val. electrons O = 6 x 1 = 6 val. electrons Total = 8 val. Electrons Step 2: Determine the central atom . (element that is only one in the molecule), which in this case is oxygen. Step 3: Draw single bond to the central atom.   How to do Lewis diagram of a molecule H H O H H O

23. Step 4: Put all the remaining electrons on atoms as lone pairs . Lewis Dot diagram for Step 5: (If needed) Turn all lone pairs into double or triple bonds to give every atom an octet or duet.   How to do Lewis diagram of a molecule H H O

24. Another Example : Step 1: Count all the no. of valence electron S = 6 x 1= 6 val. electrons O = 6 x 3 = 18 val. electrons Total = 24 val. Electrons Step 2: Determine the central atom . (element that is only one in the molecule), which in this case is oxygen.   How to do Lewis diagram of a molecule O O S O

25. Step 3: Draw single bond to the central atom. Step 4: Put all the remaining electrons on atoms as lone pairs. How to do Lewis diagram of a molecule O O S O O O S O S = 6 x 1 = 6 val. Elec. O = 6 x 3 = 18 val. Elec. Total = 24 val. Elec . Used elec. – 6 Remaining 18 vale. Elec

26. Since sulfur did not satisfy octet, we need to do step 5. Step 5: Turn all lone pairs into double or triple bonds to give every atom an octet or duet How to do Lewis diagram of a molecule O O O S S = 6 x 1 = 6 val. Elec. O = 6 x 3 = 18 val. Elec. Total = 24 val. Elec . Used elec. – 8 Remaining 16 vale. Elec

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