Chapter 2/3 notes - Chemistry
Atoms
Ancient Greek philosophers broke our plant into four main components or elements: air,
water, earth, and fire.
~ 450 B.C.E., Leucippus and Democritus
Atomos: The point at which matter can no longer be subdivided.
~384 B.C.E., Aristotle:
All matter is composed of four elements and all matter is continuous, not atomistic.
The people of that time had no way of determining which view was correct. To most of
them, Aristotle’s view of matter seemed more logic and reasonable. So, this view
prevailed for 2000 years, even though it was wrong.
An ATOM is the smallest unit of an element that has all of the properties of an element.
Pure Substances
> Elements:
- A substance that contains identical atoms
, Chapter 2/3 notes - Chemistry
- 114 known elements.
>Compounds:
- A pure substance made up of two or more elements in a fixed ratio by mass
- NaCl
Law of conservation of mass:
- During a chemical change, matter is neither created nor destroyed.
- A compound always contains the same elements in certain definite proportions.
John Dalton, Law of multiple proportions: Elements may combine in more than one set of
proportions, with each set corresponding to a different compound.
Isotopes are atoms of the same element with different relative masses. Isotopes have the
same atomic number, but have different mass numbers (same number of protons, but different
number of neutrons).
Dmitri Mendeleev Mendeleev arranged the elements in order of increasing atomic mass.
A mole is an amount of any substance or item that contain the same number of elementary
units as there are atoms in exactly 12 g of Carbon-12.
The mass, in grams, of one mole of a substance is known as the molar mass.
Chpt. 3 Notes
Electrolyte: A compound that conducts electricity when molten or dissolved in water.
Electrodes: Carbon rods or metallic strips that carry electrical current.
Electrosys
Anode: A positive electrode.
Cathode: A negative electrode.
Atoms
Ancient Greek philosophers broke our plant into four main components or elements: air,
water, earth, and fire.
~ 450 B.C.E., Leucippus and Democritus
Atomos: The point at which matter can no longer be subdivided.
~384 B.C.E., Aristotle:
All matter is composed of four elements and all matter is continuous, not atomistic.
The people of that time had no way of determining which view was correct. To most of
them, Aristotle’s view of matter seemed more logic and reasonable. So, this view
prevailed for 2000 years, even though it was wrong.
An ATOM is the smallest unit of an element that has all of the properties of an element.
Pure Substances
> Elements:
- A substance that contains identical atoms
, Chapter 2/3 notes - Chemistry
- 114 known elements.
>Compounds:
- A pure substance made up of two or more elements in a fixed ratio by mass
- NaCl
Law of conservation of mass:
- During a chemical change, matter is neither created nor destroyed.
- A compound always contains the same elements in certain definite proportions.
John Dalton, Law of multiple proportions: Elements may combine in more than one set of
proportions, with each set corresponding to a different compound.
Isotopes are atoms of the same element with different relative masses. Isotopes have the
same atomic number, but have different mass numbers (same number of protons, but different
number of neutrons).
Dmitri Mendeleev Mendeleev arranged the elements in order of increasing atomic mass.
A mole is an amount of any substance or item that contain the same number of elementary
units as there are atoms in exactly 12 g of Carbon-12.
The mass, in grams, of one mole of a substance is known as the molar mass.
Chpt. 3 Notes
Electrolyte: A compound that conducts electricity when molten or dissolved in water.
Electrodes: Carbon rods or metallic strips that carry electrical current.
Electrosys
Anode: A positive electrode.
Cathode: A negative electrode.
