Chapter 1. Chemical Foundations Flashcards
Scientific Method
The process of studying natural phenomena, involving observations, forming laws and theories, and testing of theories by experiment.
Hypothesis
One or more assumptions put forth to explain the observed behavior of nature.
Theory
A set of assumptions put forth to explain some aspect of the observed behavior of the matter.
Model
A set of assumptions put forth to explain the observed behavior of matter. The models of chemistry usually involves assumptions about the behavior of individual atoms or molecules.
Natural Law
A statement that expresses generally observed behavior.
Law of Conservation of Mass
mass is neither created nor destroyed.
Law of definite porportions
A given compound always contains exactly the same proportions of elements by mass.
Atomic Weights
The weighted average mass of the atoms in a naturally occurring element
Avogadro’s hypothesis
One or more assumptions put forth to explain the observed behavior of nature.
Cathode-ray tubes
the ‘‘rays’’ emanating from the negative electrode (cathode) in a partially evacuated tube: a stream of electrons
Electrons
A negatively charged particle that moves around the nucleus of the atom
Radioactivity
The spontaneous decomposition of a nucleus to form a different nucleus
Nuclear atom
an atom having a dense center of positive charge(the nucleus) with electrons moving around the outside.
Nucleus
the small, dense center of positive charge in an atom.
protons
a positively charged particle in an atomic nucleus.
Neutrons
a particle in the atomic nucleus with mass virtually equal to the protons but with no charge.
Isotopes
atoms of the same element ( the same number of protons) with different numbers of neutrons. they have identical atomic numbers but different mass numbers
Atomic number
the number of protons in the nucleus of an atom.
mass number
the total number of protons and neutrons in the atomic nucleus of an atom
Ion
an atom or a group of atoms that has a net positive or negative charge
Cation
A positive ion.
Anion
A negative ion.
Dalton’s Atomic Theory
All elements are composed of atoms.
all atoms of a given element are identical
chemical compounds are formed when atoms combine
atoms are not changed in a chemical reaction but the way they are bounded together change.
Thomson Model
Milikan experiment
Rutherford experiment
nuclear model
Proposed by Rutherford in in 1911 pictures the atom as a heavy, positively charged nucleus, around which much lighter, negatively charged electrons circulate.
