Upgrade to remove ads
Only $2.99/month

Chemistry Addison Wesley Chapter 5 Vocabulary

Terms in this set (33)

Democritus
The first person to suggest the existence of small particles that compose all matter, called atoms. He believed all atoms were indivisible and indestructible
Dalton's Atomic Theory
1. All elements are composed of tiny indivisible particles called atoms
2. Atoms of the same element are identical. The atoms of any one element are different from those of any other element
3. Atoms of different elements can physically mix together or chemically combine in simple whole-number ratios to form compounds
4. Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction
Atom
The smallest particle of an element that retains the properties of that element
Electrons
Negatively charged subatomic particles discovered by J.J. Thomson in 1897
Cathode Ray
The beam that traveled from the cathode to the anode
J.J. Thomson's experiment
He performed experiments that passed electric current through gases at low pressure. He sealed the gases in a glass tube that had electrodes on both ends. The electrodes were connected to a source of high voltage electricity. One electrode, the anode became positively charged. The other, the cathode became negatively charged. A glowing beam formed between the electrodes. The beam that traveled from the cathode to the anode is known as the cathode ray. He proposed that the cathode ray is a stream of negatively charged particles moving at a high speed..
Mass of an Electron
1/1840 the mass of a hydrogen atom
Proton
Positively charged subatomic particles that are located in the nucleus of the atom. Have a charge of +1. Discovered by E. Goldstein
Neutrons
Neutrally charged subatomic particles located in the nucleus of an atom. They have no charge (0).
Mass of a proton
1
Mass of a neutron
1
Atoms have
no electric charge; they are electrically neutral
Electric Charges
are always carried by particles of matter
Electric Charges exist
in whole-number multiples of a single basic unit; there are no fractions of charges
Rutherford's Experiment
Rutherford directed a narrow beam of alpha particle at a thin sheet of gold. Most of the particles passed straight through. A small number of particles bounced of the foil at a large angle
Rutherford Proposed
1) the atom is mostly empty space
2) all the positive charge and almost all the mass are concentrated in a small region that has enough positive charge to account for the great deflection of some of the alpha particles
Nucleus
The central core of the atom that is composed of protons and neutrons
Atomic Number
The number of protons in the nucleus of an atom of that element
Mass Number
The total number of protons and neutrons in an atom
Number of Neutrons
Mass Number - Atomic Number
Isotopes
Atoms that have the same number of protons but different numbers of neutrons
Atomic Mass Unit (amu)
One-twelfth the mass of a carbon-12 atom
Atomic Mass
A weighted average mass of the atoms in a naturally occurring sample of the element
Atomic Mass Formula
(Mass Isotope A)(Decimal Abundance)+(Mass Isotope B)(Decimal Abundance)
Periodic Table
An arrangement of the elements according to similarities in properties
Henry Moseley
Arranged the elements in a table by order of atomic number instead of atomic mass
Periods
Horizontal rows of the periodic table. There are 7
Group or Family
Vertical columns of the periodic table. There are 18
Periodic Law
When the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties
Metals
Elements that have high electrical conductivity and high luster. they are ductile (able to be drawn into wires) and malleable (able to be beaten into thin sheets).
Nonmetals
Elements that are generally nonlustrous and that are generally poor conductors of electricity.
Noble Gases
Also called the inert gases. Undergo very few chemical reactions
Metalloids
Elements with properties that are intermediate between those of metals and nonmetals.
THIS SET IS OFTEN IN FOLDERS WITH...