Chapter 2: What's the Matter

Definitions Pure Substance = a substance whose properties are the same throughoutMixture = combination of 2 or more pure substancesHomogeneous Mixture = Mixture whose composition is the same throughout the sampleHeterogeneous Mixture = Mixture whose compositionElement = Substance that can't be chemically broken down into simpler substances Compound = Pure substance composed of 2 or more elementsMolecule = Combination of 2 or more atoms joined togetherIsotopes = 2 or more atoms of the same element that have different numbers of neutrons

Important Words Classify Pure Substance Mixture Heterogeneous Mixture Homogeneous Mixture Greenhouse Gas Law of Mass Conservation Conservation of Mass Element Compound Malleable Brittle Joseph Louis Proust Law of Definite Proportions Antoine Laurent de Lavoisier Dalton's Atomic Theory Atoms Molecules Protons Neutrons Electrons Subatomic Particles Crooke's Tubes Plum Pudding Model Nuclear Fission Isotopes Planetary Model Nucleus

Notes Everything is made of matter.Joseph Louis Proust proposed the Law of Definite Proportions.In the early 1800's, English Philosopher John Dalton formulated Dalton's Atomic Theory.All substances in nature are composed of tiny particles called atoms.Greek philosopher Democritus was the first to propose the idea of atoms.Atoms are made up of protons (+), neutrons (=), and electrons (-).The plum pudding model of an atom had the protons everywhere like "bread" with electrons embedded like "plums".The plum pudding model was disproved in 1909 by Ernest Rutherford.Rutherford came up with the planetary model with a nucleus.In nuclear fission, large atoms are hit with neutrons, they then fall apart into 2 smaller atoms with a few extra neutrons. The mass of the final product is lower than the mass of the initial atom and neutron. The extra mass is converted into energy. This disproves the Law of Mass Conservation. However, the law still holds true for chemical purposes.Neutrons don't affect an atom's chemistry, but they do affect its mass. These variations in the amount of neutrons are called Isotopes. All naturally occurring elements have isotopes.

Dalton's Atomic theory All matter is made up of atoms, [{disproven}which are indestructible and indivisible] All atoms of a given element are identical in all (chemical) their properties Compounds are formed by a combination of 2 or more different kinds of atoms. A chemical reaction is a rearrangement of the atoms that exist in the substances which are reacting.

Laws Law of Mass Conservation = The total mass of everything involved in the experiment/reaction must remain the same Law of Definite Proportions = A given compound will always have the same proportion of elements by massLaw of Multiple Proportions = When 2 elements combine to form different compounds, a fixed amount of 1 element will combine with the other element so that the ratio of the masses of the other element is a small whole number