Form when two or more non-metal atoms SHARE electrons. There is no transfer of electrons.
Covalent Bonds What holds a covalent bond together? ______________________________________ ____________________________________
Covalent Bonds These are the three types of chemical bonds that you must know:
Covalent Bonds Using electronegativity to determine what kind of bond will form Electronegativity: __________________________
Covalent Bonds Non-Polar Covalent Bond Electronegativity values for the two atoms are equal Atoms attract electrons with the same force Electrons are shared equally.
Covalent Bonds Polar Covalent Bonds Electronegativity values differ significantly Electrons are shared unequally Electrons are found by the atom with the highest electronegativity.
Covalent Bonds Ionic Bond Review Electronegativity values are extremely different Electron spends so much time at the atom with high electronegativity, it is thought as being “transferred” to that atom
Covalent Bonds Electronegativity Difference and Bond Character Electronegativity Difference Type of Bond 0.0 – 0.5Non-polar covalent 0.6 – 1.9Polar Covalent 2.0 – 3.3Ionic
Covalent Bonds Dipoles Occur in polar covalent bonds Electrons spend more time around the atom with higher electronegative charge Gives the molecule a partial positive and negative charge called a dipole
Covalent Bonds Dipoles Symbol: Lower case Greek Delta (δ) Means “partial” δ + stands for the positive end of the molecule δ - stands for the negative end of the molecule THIS IS DOES NOT MEAN THE BOND IS IONIC! This just show where the electron is mostly likely to be located! Important!
Properties of Covalent Substances Soft Poor conductors of heat Poor conductors of electricity There are no charged particles – no ions Low melting and boiling points due to weak attraction between molecules Low solubility in water Can be liquid, solid or gas