Chemistry of Life

ProtonsNeutronsElectrons Location (within an Atom) Charge (neutral, positive or negative) Relative Atomic Size (largest, smallest…?) Complete the Table in Your Notes

Unless told otherwise atoms are neutral. – What does this tell you about the number of protons, neutrons and electrons?  Protons = electrons  Number of neutrons can vary (they do not contribute to the charge) “Anatomy of an Atom”

Atoms of same type have same number of protons! (it’s what makes an atom, an atom!)  All oxygen atoms have 8 protons Can have different number of neutrons Isotopes of the same element  Carbon-12 isotope versus Carbon-14 isotope --> Carbon-14 has TWO more neutrons Nucleus Consists of Protons and Neutrons held together by nuclear force.

Found in energy levels around the nucleus They are about 2,000 times smaller than protons or neutrons! If an atom loses an electron, it will become positively charged. If an atom gains an electron, it will become negatively charged. We call these charged atoms ions – an atom that gains or loses an electron, and has a charge. Electrons

Inter= between (think interstate) Attraction between molecules Why we have liquid water and it isn’t all gas. – Forces hold neighboring water molecules together Inter molecular forces

How does the structure of water contribute to its unique properties?

Polarity A molecule in which the charges are unevenly distributed is said to be polar because the molecule is a bit like a magnet with two “poles.” They are written as (-) negative, and (+) positive.

Adhesion An attraction of Molecules of different substances Capillary action causes water to rise against gravity (ex. roots, meniscus reading)

Hydrogen Bonding A hydrogen bond is not as strong as a covalent or ionic bond Water molecule attract each other because of their polarity Polarity allows the formation of many hydrogen bonds that count for many of water’s special properties  Cohesion  Adhesion  Heat Capacity

Cohesion An attraction of Molecules of the same substance Cohesion causes water molecule to be drawn together (beading water droplets) and causes surface tension (insects walking on surface)

Heat Capacity The large amount of hydrogen bonds causes a large amount of heat energy to move the molecules and raise the temperature. Water is said to have a high specific heat It allows large bodies of water to absorb tremendous amounts of heat and only cause small temperature changes

Solutions Waters polarity gives it the ability to dissolve ionic compounds and other polar molecules. Its is considered the Universal Solvent because it dissolves so many things. Solution : a mixture formed when one substance dissolves another Solvent : the substance doing the dissolving Solute : the substance being dissolved.

Acid/Base/pH The concentration of H+ ions on a solution is pH. Water can be split into H+ and OH- ions. Acids = a compound that forms H+ ions in the solution Base = a compound that forms OH- (hydroxide) ions in a solution Buffer = weak acids or bases that can react with strong acids/bases to prevent sudden changed in pH **Buffers dissolved in life’s fluids are important for maintaining homeostasis in an organism