Unit 2, Lesson 2.6 - Elements and Compounds Lesson Outline: 1. Matter: An Overview 2. Pure Substance 3. Element vs. Compound 4. Metals, Metalloids, Nonmetals 5. Law of Definite Composition

1. Elements and
Compounds
(Unit Two, Lesson 2.6)
By Margielene D. Judan

2. Lesson Outline:
 Matter: An Overview
 Pure Substance
 Element vs. Compound
 Metals, Metalloids, Nonmetals
 Law of Definite Composition

3. Copy the table. This will help you
distinguish classifications of matter.

4. PURE SUBSTANCE
 A form of matter
which cannot be
separated by
physical means.
 It is further classified
into two: ELEMENTS
and COMPOUNDS.

6. ELEMENTS VS. COMPOUNDS
1. Contains only one
kind of atom
1. Contains two or more
kinds of atoms
He
H
H
O
Water (H2O)Helium Oxygen (O2)
O
O

7. ELEMENTS VS. COMPOUNDS
2. Cannot decompose
by ordinary chemical
means
2. Can decompose by
chemical means.
He
H
H
O
Water (H2O)Helium atom
will not
decompose

8.  When water
decomposes, they
will separate from
each other, forming
2 helium gas, and
one oxygen gas. H
H
O

9.  That is what you see
when water boils:
the oxygen and
hydrogen steam.
Water decomposes into steam

10. ELEMENTS VS. COMPOUNDS
(SUMMARY)
1. Contains only one
kind of atom
2. Cannot decompose
by ordinary chemical
means
1. Contains two or more
kinds of atoms
2. Can decompose by
chemical means.

11. ELEMENTS VS. COMPOUNDS
(EXAMPLES)
 Oxygen (O2)
 Helium (He)
 Nitrogen (N2)
 Sodium (Na)
 Chlorine (Cl)
 and more (There are
currently 115 known
elements)
 Sodium chloride/salt (NaCl)
 Water (H2O)
 Aluminum oxide (Al2O3)
 Carbon dioxide (CO2)
 Alcohol (C2H5OH)
 Ammonia (NH3)
 Silicon dioxide/ sand (SiO2)
 etc. (There are millions of
compounds)

12. ELEMENTS VS. COMPOUNDS
(CLASSIFICATION)
1. Metals
2. Metalloids
3. Nonmetals
1. Acids
2. Bases
3. Salts

13. ELEMENTS
 Metal – conducts heat and electricity
(conductor)
 Metalloid – exhibits both properties of metal and
non-metal (conductor and insulator)
 Nonmetal – doesn’t conduct heat and electricity
(insulator)

14.  Look at your
periodic table.
Did you see a
ladder-shaped
line or pattern?

15.  The elements
adjacent to it
(colored blue)
are the
metalloids

16.  There are 7 metalloids:
1. Boron (B)
2. Silicon (Si)
3. Germanium (Ge)
4. Arsenic (As)
5. Antimony (Sb)
6. Tellurium (Te)
7. Polonium (Po)
*Antimony (At) is not a
metalloid

17.  Metals are all
elements to the
left of
metalloids.
 Nonmetals are
those to the
right of
metalloids.

18. With your Periodic Table, classify whether
they are metal, metalloid, or nonmetal.
1. Oxygen
2. Silicon
3. Calcium
4. Potassium
5. Lead
6. Boron
7. Neon
8. Iodine
9. Astatine
10. Gold

19. Answers:
1. Oxygen (nonmetal)
2. Silicon (metalloid)
3. Calcium (metal)
4. Potassium (metal)
5. Lead (metal)
6. Boron (metalloid)
7. Neon (nonmetal)
8. Iodine (nonmetal)
9. Astatine (nonmetal)
10. Gold (metal)

20. COMPOUNDS:
Law of Definite Composition
 A molecule of a compound has a definite
number of atoms.
Examples:
 H2O – 2 molecules of H, 1 molecule of O
 NH3 – 1 molecule of N, 3 molecules of H
 Vinegar (CH3COOH) – 2 mol C, 4 mol H, 2 mol O

21. According to their
electron configurations,
elements are classified as
 s block elements
 p block elements
 d block elements
 f block elements
We will not study what
these blocks mean (this is
higher chemistry) but we’ll
just use these blocks to
classify our elements.

22. Short Quiz tomorrow:
Memorize the
abbreviations and the
meanings of the
elements in the s block.

23. Sources:
 Science Links 7