Chapter 2.2.2 (Exam 1) Covalent Bonds Flashcards
Atoms Bond to Form Molecules
What are the 4 features of covalent bonds?
Strength and stability
Orientation
Multiple covalent bonds (single, double, or triple)
Unequal sharing of electrons (polar)
Describe the orientation of a covalent bond. Why is it important?
Length, angle, and direction of bonds between any two elements are always the same
Gives molecules their shapes, which contributes to their biological functions
How can molecules with covalent bonds change shape? Which structure can rotate freely?
Molecule shape can change as atoms rotate around a covalent bond
Long chains of atoms (especially carbons) can rotate freely; thus possibilities for different arrangement of atoms exist
Why is free rotation around a covalent bond an important property for molecules?
This allows molecules to alter their structures, for example, to fit other molecules
What are the types of multiple covalent bonds?
Single bonds: sharing 1 pair of electrons
Double bonds: sharing 2 pairs of electrons
Triple bonds: sharing 3 pairs of electrons
Describe bond energies in multiple covalent bonds.
Bond energy is higher and double and triple bonds because more energy is required to break the bond
Why are electrons not always equally shared in covalent bonds?
Atoms have differing electronegativity
What is electronegativity? What does it depend on?
Attractive force that an atomic nucleus exerts on electrons in a bond
The # of protons and the distance between the nucleus and electrons in the valence shell
What is a nonpolar covalent bond?
Electrons are shared equally (atoms have similar electronegativity
What is a polar covalent bond?
One atom has greater electronegativity, so electrons are drawn more to that nucleus
Polar molecules have a dipole. What does it mean to have a dipole?
They have two poles, a pole of concentrated positive charge, and concentrated negative charge
