Download Chapter 4.1 and 4.2 - science-b

Chapter 4.1 and 4.2 atomic structure
Everything in the world is made of
less than 100 types of atoms called
elements.
Everything in the world is made of less
than 100 types of atoms called elements
they combine to make compounds like
letters of the alphabet make words
In a chemical reaction, one substance
changes to another by reorganizing the
way the atoms are attached to each other
• In 1803, John Dalton proposed a
theory which accurately described
and predicted chemical behavior.
• Dalton’s four postulates are still
accepted today (with a few
modifications)
Dalton’s atomic theory- 4 postulates
all elements are composed of tiny
indivisible particles called atoms.
Dalton’s atomic theory- 4 postulates
all elements are composed of tiny
indivisible particles called atoms.
Dalton was wrong
about the “indivisible”
part, but the rest of
this tenet is still
fundamental to
chemistry.
Dalton’s atomic theory- 4 postulates
atoms of the same element are
identical. The atoms of any one element
are different from those of any other
element.
Dalton’s atomic theory- 4 postulates
atoms of different elements can
physically mix together or can chemically
combine in simple whole-number ratios
to form compounds.
Dalton’s atomic theory- 4 postulates
chemical reactions occur when atoms are
separated, joined, or rearranged. Atoms
of one element are never changed into
atoms of another element in a chemical
reaction.
Atoms are composed of protons,
neutrons, and electrons.
Atoms are composed of protons,
neutrons, and electrons.
Protons and neutrons are found in the
tiny nucleus of the atom .
The cloud that they
form is the majority of
the atom’s size.