3. Matter: Physical State and Chemical Composition
Solid: is relatively incompressible and has fixed shape and
volume
Liquid: a liquid has a fixed volume but no fixed shape.
Gas: a given quantity of gas will fit into a container of almost
any size and shape
4. Elements, Compounds, and Mixtures
Physical change is a change in the form of matter but not
in its chemical identity.
Chemical change, or chemical reaction, is a change in
which one or more kinds of matter are transformed into a new
kind of matter or several new kinds of matter
5. Substance is a kind of matter that cannot be
separated into other kinds of matter by any
physical process.
Element substances that cannot be
decomposed by any chemical reaction into
simpler substances
6. Compound is a substance composed of two or more
elements chemically combined.
Lavoisier and others examined many compounds and showed
that all of them were composed of the elements in definite
proportions by mass
Example: 1.0000 gram of NaCl
7. Mixture is a material that can be separated by
physical means into two or more substances.
Heterogenous: a mixture that consists of physically
distinct parts, each with different properties
Homogenous: a mixture that is uniform in its
properties throughout given samples.
10. Atomic Theory and Atomic Structure
John Dalton
"all matter—whether element, compound, or
mixture—is composed of small particles called
atoms”
11. Postulates of Dalton’s Atomic Theory
1.An atom is an extremely small particle of matter that retains its identity
during chemical reactions.
2.An element is a type of matter composed of only one kind of atom,
each atom of a given kind having the same properties.
3.A compound is a type of matter composed of atoms of two or more
elements chemically combined in fixed proportions
4.A chemical reaction consists of the rearrangement of the atoms
present in the reacting substances to give new chemical combinations
present in the substances formed by the reaction.
12. Atomic Symbols and Models
Atomic symbol is a one- or two-letter notation used to
represent an atom.
Example: Chloride
Sodium
13.
14.
15. John Dalton (1766–1844)
John Dalton’s theory of the atom started
out as a solid sphere with no charges
Proposed the atomic theory by investigating
the atomic weights of atoms
16. Deductions from Dalton’s Atomic Theory
Law of multiple proportions, deduced by Dalton from his atomic
theory, states that when two elements form more than one
compound, the masses of one element in these compounds for a
fixed mass of the other element are in ratios of small whole
numbers
17. Example: There are compounds made up of the
same elements, like carbon monoxide and
carbon dioxide.
18. J.J. Thomson determines that an atom is
made up of negative electrons embedded in
a sea of positive charges.
+
-
-
-
-
+
+
+
19. Ernest Rutherford did some experiments with
thin metal foils and found that the positive
charge is located within a central nucleus
20. Neils Bohr worked under Rutherford but found problems
with his theory. He ultimately determined that Electrons
are in circular orbits with increasing energy levels.
21. The modern atomic model shows that electrons
occupy regions of space whose shape is described
by complex mathematical equations.
22. History of Atomic Theory
John Dalton’s theory of the atom started out as a solid sphere
with no charges.
J.J. Thomson figured out there were positive and negative
charges in an atom.
Rutherford determined that the positive charges (protons)
were located in the center of the atom and the negative
charges (electrons) were scattered around the nucleus
23. History of Atomic Theory
Bohr’s theory said that the protons are in the
middle and the electrons travel in specific energy
levels and orbit around the nucleus
Modern model- protons and neutrons in the
nucleus, electrons on energy levels
24.
25. Atoms form Ions
Ions: formed when an atom
loses or gains one or more
electrons
Cation: formed when an
atom loses an electron
Anion: formed when an
atom gains an electron
26.
27. Elements are organized by similarity
Dmitri Mendeleev began
organizing elements by
their physical and
chemical properties
(1860’s)
28. Periodic Table of
the Elements
Called the periodic table because
a periodic, or repeating pattern
of properties of the elements
29. Periodic Table
Period: each row of the periodic table is
called a period.
Group/Family: Each column of the table is
called a group or family.
32. Periodic Table has distinct regions
Reactive: indicates how likely an element is to
undergo a chemical change
The most reactive are in groups (up/down)
The least reactive are in group (up/down)
33. Elements combine by the outside
electrons
Valence Electrons: Only the electrons in
the element’s outside energy level interact
with each other.
The most stable configuration has 8
electrons in the outer energy level.
Elements in group 1 have 1 electron in the
outside energy level Elements in group 17
have 7 electrons in the outside energy level
34. Example:
Elements in group 1 have 1 electron in the outside energy
level Elements in group 17 have 7 electrons in the outside
energy level
35. Metals
Metals are elements that
conduct electricity and
heat, have shiny
appearance, and can be
shaped by pounding
(malleability), bending, or
being drawn into a thin
wire (ductility)
39. Nonmetals
Nonmetals: the elements on
the right side of the periodic
table
Many are gases at room
temperature, dull surfaces
on the solid nonmetals,
cannot be shaped by ductility
or malleability
42. Metalloids
Have properties of both
metals and nonmetals
Located on either side of the
zigzag line separating metals
and nonmetals
43. Radioactivity
Radioactivity: the process by
which the nucleus of an atom
releases energy and particles
Marie Curie was the first person
to isolate two radioactive
elements
