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Matter
- anithing that takes up space and has mass
- can exist as solid, liquid, or gas
- all matter is composed of chemical elements
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Element
a pure substance that cannot be broken down into other substances
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Mass
- 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
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Atomic number
is the number of protons in the nucleus
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Isotopes
Different type of atom of the same chemical element, each having a different number of neutrons
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Molecular formula
- CO2 Tells two pieces of info:
- Describes which types of atoms are in a molecule and how many of each
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Structural formula
- two-dimentional representations of a given molecule
- Each line represents one shared pair of electrons
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Chemical bondings
- Covalent bonding: polar and non polar
- Ionic Bonding:
- Hydrogen Binding:
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Covalent bonds
- 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
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Ionic Bond
- 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.
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Hydrogen Bonding
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
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Electronegativity
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
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Polarity
a difference in electrical charge at one end as opposed to the other.
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Water as a good solvent
- 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
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Solution
mixture of two or more kind of molecules
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Solute
what is being disolved
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Solvent
what disolves other substances
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Acids and Bases
- 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
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pH
- 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
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