Download Chemical compounds

CHEMICAL COMPOUNDS
LEARNING GOALS
• We are learning about chemical compounds.
• We are learning to identify parts of chemical formulas.
• We are learning to identify two types of chemical compounds.
CHEMICAL COMPOUNDS
• Formed from elements in periodic table
• Formed from 2 or more elements
• We use them in every day life!
CHEMICAL COMPOUNDS
• Have an official name and a chemical name
• Can be identified by words and symbols
REACTIVITY
• The closer to an atom is to a full outer electron shell, the more reactive it is
• How likely an atom will take part in a chemical reaction and form a compound
• The atoms of group 18 are not reactive at all
• Noble gases
• Full outer electron shell
TRY THIS
1. Name the least reactive group of elements. Why?
• Nobel gases! Full outer shell!
1. Name the two most reactive. Why?
• Alkali (grp 1) and Halogens (grp 17). One electron away from noble gas!
1. Name the element in each pair that is more reactive:
a) Na and Mg
b) S and Cl
c) K and Na
d) F and Cl
CHEMICAL FORMULAS
• A group of letters and subscript numbers that represent the make-up of a
chemical compound
symbol for
element hydrogen
Small number here
means 2 atoms of
hydrogen
symbol for
element oxygen
H2O
No small number
here means 1 atom
of oxygen
TRY THIS
1. CaCO3
6. C6H12O6
2. Na3PO4
7. CO2
3. MgCl2
8. CCl2F2
4. NaC5H8NO4
9. CH2F2
5. H2O2
PLEASE COMPLETE
1. What does the subscript in a chemical formula tell you?
2. What does no subscript mean?
3. For the compound ammonia, NH4, how many nitrogen atoms are there, and
how many hydrogen atoms are there in each molecule?
4. Write a chemical formula for a compound that is made of one atom of
carbon (C) and 4 atoms of hydrogen (H)?
5. Write the chemical formula for a compound that has two atoms of nitrogen
and four atoms of oxygen.
STABILITY
• When elements form compounds, they become more stable.
• All elements try to achieve a full, stable outer electron shell that noble gases
have.
STABILITY
• Elements achieve a full shell in one of three ways:
1. Metals lose electrons to form positive ions.
2. Non-metals gain electrons to form negative ions.
3. Non-metals share electrons.
IONS
• An atom or group of atoms that has an electrical charge.
• Can be either positive or negative.
TYPES OF COMPOUNDS
• Two types:
1. Ionic
2. Molecular
IONIC COMPOUNDS
• Metal ions are positively charged
• Non metal ions are negatively charged
• Ionic compounds form because metal ions and non-metal ions are attracted to
each other.
IONIC PROPERTIES
• Solid at room temperature
• Very high melting points
• Conduct electricity when melted or dissolved in water
MOLECULAR COMPOUNDS
• Non-metal atoms can share electrons with other non-metal atoms
• Hydrogen is included here
MOLECULAR PROPERTIES
• Solids, liquids, or gases at room temperature
• Lower melting points than ionic compounds
• Do not conduct electricity when melted or dissolved in water
IONIC OR MOLECULAR
1. NaCl
• CCl4
2. CH4
• CaO
3. CO
• MgO
4. CaCl2
• CuBr2
5. C12H22O11
• CH3OH
LEARNING GOALS
• We are learning about chemical compounds.
• We are learning to identify parts of chemical formulas.
• We are learning to identify two types of chemical compounds.