Bonds Between Atoms Covalent Ionic Polyatomic Ions Metallic Molecular Substance Polar Nonpolar What are we going to learn about???
The following words will be used most lessons… Anion- negative ion Cation-positive ion Octet Rule- rule that states that atoms tend to gain, lose, or share electrons so that each atom has full outermost energy level which is typically 8 electrons. Polyatomic Ion- charged group of covalently bound atoms Monatomic Ion- ion formed from a single atom Molecule-neutral group of atoms united by covalent bonds Valence electrons- an atoms outer most electrons. Unshared Pair- pair of electrons that is not involved in bonding but instead is held exclusively by one atom.
Marriage Divorce Forming of a bond is like marriage More stable exothermic The breaking of a bond relates to a divorce. Less stable Endothermic
Ionic Bonds What is an Ionic Bond? - An Ionic Bond is a chemical bond resulting from the TRANSFER of electrons from one bonding atom to another When is an ionic bond formed? - An ionic bond is formed when a cation (positive ion) transfers electrons to an anion (negative ion). Metal + Nonmetal → Ionic
What are some characteristics of an ionic bond? 1.Crystalline at room temperatures 2.Have higher melting points and boiling points compared to covalent compounds 3.Conduct electrical current in molten or solution state but not in the solid state 4.Soluble in H 2 O 5.Strong electrostatic attractive forces between ions
Metallic Bonding What is a Metallic Bond? - A metallic bond occurs in metals. A metal consists of positive ions surrounded by a “sea” of mobile electrons. Metallic Bond Characteristics 1.Good conductors of heat and electricity 2.Great strength 3.Malleable and Ductile 4.Luster This shows what a metallic bond might look like.
Metals are Malleable Hammered into shape (bend). Ductile - drawn into wires. Electrons allow atoms to slide by. ++++ ++++ ++++
Covalent Bonds What is a Covalent Bond? - A covalent bond is a chemical bond resulting from SHARING of electrons between 2 bonding atoms. What forms a covalent bond? - A covalent bond is formed between two nonmetals. Nonmetal+ Nonmetal → Covalent
What are some characteristics of a covalent bond? 1.Covalent bonds have definite and predicable shapes. 2.Low melting solides, Liquids or Gases at normal temperatures. 3.Bonds stretch, bend, rotate 4.Low melting and boiling points 5.Not usually soluble in water 6.Not electrically conductive
Covalent Bonds can have multiple bonds, so you should be familiar with the following… Single Covalent Bond- chemical bond resulting from sharing of an electron pair between two atoms. Double Covalent Bond- chemical bond resulting from sharing of two electron pairs between two atoms. Triple Covalent Bond- chemical bond resulting from sharing of three electron pairs between two atoms.
There are five different categories associated with covalent bonds. We will talk about only three. Covalent Molecular Substance Polar Nonpolar Coordinate Covalent Network Solids
Polyatomic Bonds What is a Polyatomic Bond? - A polyatomic bond is charged group of covalently bonded atoms. It is made up of more than one atom. Polyatomic ions usually have a charge because the collection of atoms has either gained an extra electron or else it has lost an electron.
Electronegativity Trend –Increases up and to the right. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electronegativity Difference Determines type of bond that will form between two atoms. Ionic Polar-covalent Nonpolar-covalent 3.3 1.7 0.5 0 100% 50% 5% 0% Difference in electronegativities Percentage ionic character Low Difference ( < 1.7) a sharing of electrons in a bond (covalent bond) Weaker bond High Difference ( > 1.7) a Transfer of electrons in a bond (ionic bond) Stronger bond