2 Basic ChemistryATOM: The basic building block of all matter; the smallest particle of an element that still retains properties of that elementAll atoms have a Nucleus, which is the central part of the atom; it contains protons; and has an overall positive charge.PROTON: (+)ve charged subatomic particles located in the nucleus; charge of +1NEUTRON: (-/+) neutral (no charge) subatomic particles located in the nucleus; charge of 0.Protons and neutrons have about the same mass.ELECTRON: (-) Negatively charged subatomic particles located in electron orbitals around the nucleus; their mass is tiny, about 1/1840 the mass of a proton; charge or -1
3 Atoms have equal numbers of protons and electrons, their overall charge is zero (neutral)
4 ELEMENT – Matter containing only one type of atom. SYMBOLATOMIC NUMBERThe number of protonsATOMIC MASSThe number of protons + neutron
14 Properties of Water Water covers ¾ of Earth’s Surface Water is the single most abundant compound in most living things.
15 The Water MoleculeWater has several important physical properties:It is a liquid at temperatures found over much of Earth’s surface.Water expands as it freezes.Water is more dense than ice, so ice floats. Which allows for fish and plant life to survive below the ice.
16 The Water Molecule Overall, water is a neutral molecule. However, a water molecule is polar.Although the entire molecule has equivalent numbers of protons and electrons, the electrons are unevenly distributed.
17 The Water MoleculeThe oxygen has a strong pull on the electrons near the oxygen making the probability of finding those electrons near the oxygen greater than finding them near the hydrogen atoms.This gives the oxygen end of the water molecule a slightly negative charge and the hydrogen ends of the water molecule a slightly positive charge.This uneven distribution of charge on a molecule is called polarity.When large numbers of water molecules get together, hydrogen bonding occurs.
18 Properties of WaterCOHESION – an attraction between molecules of the same substance.An example of cohesion is called surface tension- water molecules on the surface of a body of water cling tightly together and allow small organisms to survive on its surface.ADHESION – an attraction between molecules of different substances.Cohesion and adhesion work together to produce capillary action.
19 The water moleculeADHESION – an attraction between molecules of different substances.Cohesion and adhesion work together to produce capillary action.Adhesive forces cause the water to climb up the inside of the alls of the tubes, and cohesive forces allow the water molecules to cling to each other as it crawls up the tube.
21 Solution and Suspensions Water is often found as a - a material composed of substancesthat aremixturetwo or morephysically mixed together.Example:1) Dissolving sugar into hot tea2) Dissolving salt into hot water
22 Solution and Suspensions Two types of mixtures can be made with water:Solution – a mixture where a substance is evenly mixed in another substance.The substance in the smallest amount, which isis called theThe substance in the greatest amount, whichdissolvedsolute.dissolves the solutesolvent.
23 Solution and Suspensions Waterhas the ability to dissolve many substances and thus is called theGeneral Solubility Rule:universal solvent.- Like dissolves likePolar substances dissolve polar substances
24 MIXTURE – mixed but not chemically combined. SOLUTION – uniform mixtureSOLVENT – dissolves other substances.SOLUTE – dissolves in the solvent.SUSPENSION – temporarily mixed
25 Acids, Bases, pH Water can react and divide/dissolve into two ions: H2O H OHScientists have devised a scale to measure the amount of hydrogen ions that exist in solutions called pH.-+
26 Acids, Bases, pH The pH scale ranges from 0-14. When a solution has an equal number of H and OH ions such as water, it is assigned a neutral pH, which is 7 on the pH scale.When a solution has a high H concentration then it is assigned an acidic pH, which is a number less than 7 on the pH scale.When a solution has a low H concentration then it is assigned a basic pH, which is a number greater than 7 on the pH scale.+--++
28 Acids, Bases, pHThe pH inside human cells must be kept close to neutral, between 6.5 and 7.5. If a chemical with a lower or higher pH enters the cell, it could disrupt chemical reactions there and thus disrupt the cell’s homeostasis.
29 Acids, Bases, pHTherefore, cells contain weak acids or bases called buffers which work to prevent changes in pH inside cells that are too acidic or too basic.For example, the skin has a surface film that is acidic and it acts as a buffer against strong bases like Clorox.