Chapter 4 chemistry study guide

Democritus
Reasoned that atoms were indivisible and indestructible.
Atom
The smallest particle of an element that retains its identity in a chemical reaction.
Dalton
Transformed Democritus ideas on atoms into a scientific theory.
Dalton’s Atomic Theory 1.
All elements are composed of tiny indivisible particles
Dalton’s atomic theory 2.
Atoms of the same element are identical. The atoms of any one element are different from those of another.
Dalton’s atomic theory 3.
Atoms of different elements can physically mix together or can chemically combine in simple whole number ratios to form compounds
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Dalton’s atomic theory 4.
Chemical reactions occur when elements are separated from each other, joined, or rearranged in a different combination.
Electrons
Negatively charged subatomic particles
Cathode Ray
Experiment performed by Thomson. One electrode became positively charged, one became negative. The result was a glowing beam.
Robert A. Millikan
Carried out experiments to find the quantity of an electrons charge. Oil drop experiment.
Electron charge
One unit of negative charge
Electrons mass
1/1840
Electron charge
1-
Proton charge
1+
Neutron charge
Protons
Subatomic positively charged
Neutron
Subatomic negatively charged
Thomson discovery
The electrons
Thomson model
Plum pudding model
Rutherford
Good foil experiment
Nucleus
Tiny central core of an atom and is composed of protons and electrons
Nuclear atom
Has a positively charged nucleus. Electrons are distributed around the nucleus and occupy almost all the volume of the atom.
Elements are different
They all contain a different number of protons
Atomic number
The number of protons in that element.
Mass number
The total number of protons and neutrons
Isotopes
Atoms that have the same number of protons but different numbers of neutrons.
Isotopes difference
They have different mass numbers because they have a different number of neutrons.
Atomic mass unit (amu)
1/12 of the mass of a carbon atom
Atomic mass
Weighted average mass of the atoms naturally occurring sample of the element.
Calculating atomic mass
Mass of each isotope x natural abundance, and then add the products.