What is special about water? (lab) Properties of Water

The study of the chemical makeup of everything. The study of chemicals made ONLY by living things.

The basic unit of matter that makes up EVERYTHING! Atoms have 3 parts: Proton- + Neutron- no charge Electron- -

Examples: Carbon (C), Oxygen (O), Hydrogen (H), Sodium (Na) *One CAPITAL letter = 1 atom

Isotopes- Have same # protons, but different # neutrons Radioactive Isotopes- Atoms whose nuclei break down at a predictable rate, giving off neutrons over time. Example- Carbon 14 How do we use this?

groups of different atoms bound together, called COMPOUNDS. Bond holding them together is stored ENERGY

Multiple atoms found BOUND together by chemical energy - often because the atoms are sharing their electrons Examples: - water H 2 O - salt NaCl - carbon dioxide CO 2 - glucose C 6 H 12 O 6

Some compounds don’t share electrons evenly. Because of this, parts are slightly positive or slightly negative. This makes them stick together like sides of a magnet. WATER IS POLAR!

H 2 O: Water is made of 2 Hydrogen atoms and 1 Oxygen atom OHHOHHH

Polarity of Water- the uneven sharing of water’s electrons OHHOHHH More Electrons - charge Less Electrons + charge

Hydrogen bonds- bonds holding water to other water *polar molecules will be attracted to other polar molecules, but DO NOT like non-polars (think water and oil). OHHOHHH OHHOHHH + -

Surface tension- Because water molecules stick together, the molecules form a barrier at the surface that, as a force, act to keep things out Ex- belly flop! OHHOHHH More Electrons - charge Less Electrons + charge

pH- Measuring the H+ (hydrogen ion) concentration in a mixture. Acids- A compound giving off H+ in a solution. pH <7 = acidic Bases- Compounds giving off OH- in a solution (creating lower concentrations of H+). pH >7 = basic

What is one way that water’s sticky properties help life exist? (lab) Properties of Water