Ch 2

• anithing that takes up space and has mass
• can exist as solid, liquid, or gas
• all matter is composed of chemical elements

a pure substance that cannot be broken down into other substances

• measures the quantity of matter in any given object (wieght)
• Protons wiegh one atomic mass unit
• Neutrons weigh one atomic unit
• eletrons have no mass

is the number of protons in the nucleus

Different type of atom of the same chemical element, each having a different number of neutrons

• CO2 Tells two pieces of info:
• Describes which types of atoms are in a molecule and how many of each

• two-dimentional representations of a given molecule
• Each line represents one shared pair of electrons

• Covalent bonding: polar and non polar
• Ionic Bonding:
• Hydrogen Binding:

• Formed when two atoms share one or more pairs of outer-shell electrons
• Nonpolar covalent bond: electrons are shared equally, charges are symmetric meaning no difference in electrical charge at one end as opposed to the other.
• Polar covalent bond: has opposite charges on opposite ends, some atoms have greater electronegativity

• Attraction between oppositely charged ions.
• Formed when one atom gives up one or more electrons to another atom
• Ion: an atom that has either a positive or negative charge, due to haveing an unequal number of protons and electrons.

weak attractions between two molecules of water in which a partially positive charged of H atoms is attracted to partially negatively charged Oxygen creating a weak attractions. Water is a polac covalent molecule

its a term to measure this kind of pull - When one atom has a greater power to attract electrons to itself than the oter atom

a difference in electrical charge at one end as opposed to the other.

• Solvent for other polar molecules
• By dissolving ions and molecules, water allows chemical reactins to occur
• High speacific heat: the amount of energy required to raise the temprature or a substance by 1 C.
• It takes longer for water to warm up.
• Ice floats because solid form of H2O is less dense, formed a maximum number of Hydrogen bonds with each other.
• Cohesion: tendency of water molecules to stick together. Cohesion give water surface tension

mixture of two or more kind of molecules

what is being disolved

what disolves other substances

• Whan water dissociates, it releases an equal number of hydrogen ions (H+) and hydroxide ions (OH-)
• Acids: substances that release hydrogen ions in solution
• Bases: substances that accept hydrogen ions or yeild hydroxide ioins in solution

• pH scale: descirbes the acidity of a solution
• pH stands for "potential hydrogen" or "hydrogen power"
• The lower the pH, the higher the concentration of H ions
• THe higher the pH, the lower the concentration of H ions
• It is a logarithmic scale - pH of 2 is 10 times more acidic than pH of 3 and 100 more acidic than pH 4