Biology Chapter 2

one pair of shared electrons (notated H-H, H:H, or H₂)

two pairs of shared electrons ...oxygen had 6 valence electrons so when two O atoms for a molecule they share two pair of electrons (notated, O=O or O₂₎

The attraction of a particular kind of atom for the electrons of a covalent bond.

The more electronegative an atom, the stronger it pulls shared electrons toward itself.

tow atoms of the same element are equally electronegative. The tug of war will result with them sharing the electrons equally. H₂ or O₂ are nonpolar covalent bonds

when one atom is bonded to a more electronegative atom the electrons are not shared equally

Water - Oxygen is very electronegative so the electrons spend more time near the nucleus of oxygen and further from the nucleus of hydrogen (this give oxygen a partial negative charge and hydrogen a partial positive charge)

Weak bonds

ever changing regions of negative and positive charge that enable atoms and molecules to stick to one another when they are close together

making and breaking of chemical bonds that lead to changes in the composition of matter

the materials involved in a chemical reaction

the result of a chemical reaction

• 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂
• carbon dioxide and water result in glucose and oxygen

when forward and reverse chemical reactions are occuring at the same rate

amount of heat it takes to raise the temperature of 1g of water by 1°C. also the amount of heat released when 1g of water cools by 1°C

kilocalorie - 1000 cal - the heat required to raise the temperature of 1 kg of water by 1°C

amount of heat that must be absorbed or lost for 1g of that substance to change temperature by 1°C

quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state

as liquid evaporated the surface of the liquid that remains behind cools down. The "hottest" molecule are more likely to leave as gas, leaving behind the cooler molecules

the sphere of water around each dissolved ion

any substance that has an affinity for water

does not have to dissolve - cotton has an affinity for water but does not disolve