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COVALENT BONDING

COVALENT BONDING. COVALENT BONDS. Covalent bonds = Sharing electrons Octet rule: Atoms still need to become stable by having 8 electrons in their outer energy level!! Instead of losing or gaining valence electrons, atoms in covalent bonds share valence electrons

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COVALENT BONDING

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  1. COVALENT BONDING

  2. COVALENT BONDS • Covalent bonds = Sharing electrons • Octet rule: Atoms still need to become stable by having 8 electrons in their outer energy level!! • Instead of losing or gaining valence electrons, atoms in covalent bonds share valence electrons • These bonds take place between nonmetals and nonmetals

  3. COVALENT BONDS • Atoms that combine through covalent bonds (electron sharing) form molecules • Example: Nonmetal

  4. COVALENT BONDSCompound Properties • Have lower melting and boiling points than ionic compounds - No bonds to be broken as in ionic compounds - Molecules are very close to each other, but not bonded • Are soft and “squishy,” compared to ionic compounds - Molecules move very easily around each other because there are no bonds between them - These makes them flexible and not hard http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/bom1s2_11.swf

  5. COVALENT BONDSCompound Properties • They are more flammable than ionic compounds - Most covalent compounds have carbon and hydrogen which burn very easily with oxygen - Those without carbon and hydrogen do not burn • They do not conduct electricity in water - Ion (charge carriers) movement in water is the conduction of electricity - Covalent compounds do not have ions • They are usually not very soluble in water - “Like dissolves like” rule - Compounds dissolve in compounds with similar properties - Water is polar solvent and most covalent compounds are nonpolar = then do not dissolve in water

  6. Single covalent bonds • Made up of two shared electrons • Usually, one of the shared electrons comes from one of the atoms in the bond and the other electron from the other atom in the bond • Halogen (Group 7A) elements exist as molecules of single covalent bonds (more stable) • Example: Hydrogen molecule (H ) 2

  7. Single covalent bondsHydrogen Molecule . . . . H H H H + Each hydrogen atom has 1 valence electron Bonding pair Another way to represent the hydrogen covalent bond: H H Bonding pair http://web.jjay.cuny.edu/~acarpi/NSC/5-bonds.htm

  8. Single covalent bondsWater Molecule . . . . . . . . . . . . . H H . O + H O + . . H OR . . . . O H H http://web.jjay.cuny.edu/~acarpi/NSC/5-bonds.htm

  9. Multiple Covalent Bonds • Covalent bonds can have more than one pair of shared electrons • Atoms of the elements carbon, nitrogen, oxygen, and sulfur very often form multiple covalent bonds • Multiple bonds can be double or triple covalent bonds

  10. Double covalent bondsOxygen Molecule . . . . . . . . . . . . . . . . . . . O O O . O + Each oxygen atom has 6 valence electrons Bonding pairs

  11. Triple covalent bondsNitrogen Molecule . . . . . . . . . . . . . . N N N N + Each nitrogen atom has 5 valence electrons Bonding pairs http://www.tutorvista.com/content/chemistry/chemistry-i/chemical-bonding/covalent-bond-animation.php

  12. How do elements combine?

  13. Naming Covalent Compounds • Names are usually composed of two words - First is the name of the first element in the formula - Second is the name of the second element in the formula, but changing the ending to –Ide Example: HF = hydrogen fluoride

  14. Naming Covalent Compounds • If there is more than one atom of an element in the molecule, then we need to use prefixes to tell us how many are there

  15. Naming Covalent Compounds • Some common names to some very important covalent compounds 2 3 2 4

  16. Naming Covalent Compounds • Examples…… P O = diphosphorus pentaoxide CO = carbon monoxide CF = carbon tetrafluoride 2 5 4

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