Grade 9 Chemical Bonding.pptx

chemical bonding

1. Ch e m i c a l B o nd i ng

2. CHEMICAL BONDING is a lasting attraction between  atom s ,  ions  or  molecules  that enables the formation of  chemical compounds . The bond may result from the  electrostatic force  of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in  covalent bonds . The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent,  ionic  and  metallic  bonds, and "weak bonds" or "secondary bonds" such as  dipole–dipole interactions , the  London dispersion force  and  hydrogen bonding .

3. ELEMENTS are pure substances made up of one kind of material. Elements are classifies as metals , non metals and metalloids .

4. SYMBOL ELEMENTS LATIN NAME Na Sodium Natrium K Potassium Kalium Fe Iron Ferrum Cu Copper Cuprum Ag Silver Argentum Sn Tin Stannum Sb Antimony Stibium Hg Mercury Hydrargyyrum Au Gold Aurum Pb Lead Plumbum

5. CLASSIFICATION OF ELEMENTS M ETALS metals are mostly solid in form, except for mercury, they possess luster and they shine when light falls on them. Examples: Magnesium Platinum Nickel Iron Silver

6. Non metals exist in solids, liquids, and gases. They are usually light in weight. They are used as insulators because they are poor conductors of heat and electricity. Examples : Carbon Phosphorus Sulfur Iodine Bromine Non Metals

7. metalloids are elements that have properties of both metals and non metals. Metalloids are solid but lack luster. Examples: Boron Silicon Arsenic Metalloids

8. COMPOUNDS C ompounds are the combination of two or more elements that are chemically combined. W hen elements are combined to form a compound, elements lose their own identity and characteristics. The new substance formed has different characteristics and properties from the original elements . E xample , hydrogen (h) and oxygen (o) are both gases. they combined to form water (h20). they combine with a definite proportion. water (h2o) has 2 atoms of hydrogen and 1 atom of oxygen. C ompounds could be written in a chemical formula, a chemical formula is an arrangement of symbols and numbers that describe a compound. H2o is a chemical formula of one molecule of water.

9. KINDS OF COMPOUNDS ACIDS Acids are compounds that produce hydrogen ions when dissolved in water. Some acids are weak and some are strong. Acid can cause certain chemical dyes called indicators to change color. Indicators is a substance that change color at certain range of Ph values.

10. ACIDS NAME FORMULA Nitric HN Perchloric HCL Sulfuric Hydrobomic HBr Carbonic Hydrochloric HCL ACIDS NAME FORMULA Nitric Perchloric Sulfuric Hydrobomic HBr Carbonic Hydrochloric HCL

11. BASES Bases are compounds that produce hydroxide ions when dissolved in water. Bases usually feel slippery and have bitter taste.

12. Io n i c B o nd

13. THE OCTET RULE Everyone is seeking for stability. STABILITY refers to the strength to stand or a resistance to chemical change or physical change. If humans seek stability, so are the atoms. Stability in atoms involves the possession of eight (8) electrons in its outermost energy level or valence electrons. Atoms of all elements, therefore, to become stable, need to have 8 valence electrons. We call this the OCTET RULE which was proposed by Gilbert Newton Lewis, an American Chemist. Lewis spent one year in the Philippines as the superintendent of the Bureau of Weights and Measures.

14. VALENCE ELECTRON The Configuration of electrons and valence electrons are highly important in the study of chemical bonding. ELECTRON CONFIGURATION refers to the distribution of electrons at different positions in an atom. It becomes more complex as you move along the periodic table due to an increase of atomic number and, therefore, an increase of energy level of atoms. On the other hand, VALENCE ELECTRON are the electrons occupying the highest energy level in an atom.

15. Electron Configuration of the First 10 Elements Element Symbol Atomic Number Electron Configuration Number of Valence Electrons Group H 1 1 1 1 He 2 1 2 8 Li 3 1 1 1 Be 4 1 2 2 B 5 1 3 3 Electron Configuration of the First 10 Elements Element Symbol Atomic Number Electron Configuration Number of Valence Electrons Group H 1 1 1 He 2 2 8 Li 3 1 1 Be 4 2 2 B 5 3 3 C 6 1 4 4 N 7 1 5 5 O 8 1 6 6 F 9 1 7 7 C 6 4 4 N 7 5 5 O 8 6 6 F 9 7 7 Ne 10 1 8 8 Ne 10 8 8

16. Lewis Electron Dot Structure (LEDS) A system known as LEDS, proposed by Gilbert N. Lewis, is used to emphasize the atom’s valence electrons. It is a shorthand method which consists of a symbol of the element surrounded by dots. The symbol represents the nucleus of the atom; while the dots represent the valence electrons of the atom.

17. C o v a l e nt B o nd

18. Covalent Bond The second type of chemical bond is covalent bond. Unlike ionic bond, elements involved in covalent bonds do not transfer electrons but instead they share electrons. This type of bond exists between nonmetals.

19. Formation of Covalent Compounds When two or more nonmetallic elements combine in a covalent bonding, a molecule is formed. Gases like O2, H2, F2, Br2, and I2 always occur as diatomic molecule. As such, they are more stable than single atoms.

20. Three Types of Covalent Bond A single covalent bond, denoted by one short line (-), is the sharing of one electron pair between two atoms. A double covalent bond, denoted by two short lines (=), is the sharing of two electron pairs. A triple covalent bond, denoted by three short lines, is the sharing of three electron pairs.

21. Molecular Geometry In molecular geometry, the bond lengths and angles determined experimentally. A simple procedure known as the VALENCE SHELL ELECTRON REPULSION (VSEPR) can help predict the geometric arrangement of atoms in molecules.

22. Linear The shaped is produced when two groups try to get as far away from each other as they can. In HgCl2, molecule, mercury atom with two electrons in its valance shell is used to form covalent bond with one electron of chlorine atom producing a linear shape molecule. Cl – Hg – Cl As you notice, the HgCl2, molecule adapts a shape where its two electron pair bonds are as far away from each other as possible. The shape is linear since the central atom has two bonding electron pairs in its valence shell. In addition to linear, the angle between ion pair sand central atom is 180°.

23. Trigonal Planar Consider the boron trifluoride (BF3) molecule. Boron’s three valence electrons are supplied with one electron of fluorine to form single bond BF3. This shape is formed when three pairs get as far apart from each other as possible. The angle formed by any two bonds in the molecule is 120°.

24. Tetrahedron This structure is a common one. Many nonmetals and ions have this structure. One of which is methane, CH4. In a methane molecule, carbon has four bonding pairs of electrons in its valence shell. The bond angle for tetrahedron is 109.5°.

25. Trigonal Bipyramid When there are five electron pairs, trigonal bipyramid structure is formed. One good example for this is PCl5 molecule. The five valence electrons of phosphorus atom form five boding pairs with electrons from five chlorine atoms. Unlike tetrahedron which bonds are equidistant, the distance of trigonal bipyramid bonds are not equal.

26. Octahedron Sulfur hexafluoride (SF6) is one of the few molecules that have this structure. Six bonding pairs are present in which all the positions are equivalent, all the bond distances are equal, all the angles formed by any adjacent bonds are 90°.

27. M e t a ll i c B o nd

28. Metallic Properties Metallic solids have special properties that separate them from other solids. Metallic elements, as what we know, are located at the left side of the periodic table. A distinct ladder-like line separates them from the nonmetals. The position gives an important clue regarding the nature of how they are bonded together to form solids. Metals are malleable, ductile, and have high melting point. They are good conductors of heat and electricity as well.

29. Metals have high melting points. This is due to the electrostatic attraction between the lattice of metal cation and fluid of valence electrons in which they are immersed.

30. Metallic compounds are known to be malleable and ductile. As you know, malleability is the ability of metals to be shaped by pressure, either by hammering, rolling into sheets, or forging. On the other hand, ductility is the ability of metals to be drawn into a wire.

31. Luster is another distinct property among metals. Luster is the ability to shine and reflect light. The presence of free electrons that vibrate and move are the reasons why metals reflect light.