UNIT 1 – PHYSICAL SCIENCE AND CHEMICAL REACTIONS
CHAPTER 5: CHEMICALS IN ACTION
chemistry: the study of matter
matter: anything that has mass and occupies space
MATTER
mixtures
SUBSTANCES
PURE
COMPOUNDS
ELEMENTS
molecular
metal
ionic
non-metal
pure substance: is one in which all the particles that make up the substance are the
same; has constant properties. Atoms are in a fixed ratio.
eg. (H2O(ℓ))
mixture: contains two or more pure substances not in a fixed ratio
 eg. sugar + water  sweet water
(solute) + (solvent)  (solution)
element: a pure substance composed of only one type of atom (eg. Iron (Fe))
 Cannot be broken down by ordinary chemical means (eg. heating, electricity,
filtration, distillation, magnets)
Metals
 Found on left hand side of staircase line
 Shiny
 Ductile, malleable
 Hard
Non- metals
R.H.S. of P.T.
Dull
Brittle
soft
Ductile – the ability to be formed into a wire
Malleable – the ability to be stretched by hammering or rolling
compound: pure substance composed of at least two types of elements (or atoms)
 eg. water (H2O(ℓ)); salt (NaCl(s))
Ionic
Molecular
Composed of 2 or more ions ( metal + non-metal) 2 or more non-metallic atoms
Held together by an ionic bond
covalent bond
(e.g.) NaCl- sodium chloride
CO2 – carbon dioxide
The Modern Periodic Table
Facts about hydrogen
Group IA
 1 valence electron
 Loses 1 electron to form a hydrogen ion
Group VIIA
 1 less electron than a Noble Gas
 A gas
Can gain 1 electron to form a hydride ion
Periodic Table
 Demitri Mendeleev created the first useable periodic table
 It became the most predictive device in all chemistry
 Elements are arranged in increasing order of Atomic Number (AN)
 The periodic table is divided into vertical columns (families/groups) and horizontal rows (periods)
Atomic Number: (AN) the number of protons (p+) in the nucleus of an atom
Group A Elements
IA ~ Alkali Metals
 Soft, reactive
IIA ~ Alkaline Earth Metals
 When compared to IA; harder or not as reactive
IIIA ~ Aluminum Group
IVA-VIA ~ Name according to first element in group
VIIA ~ Halogens
 Very reactive
VIIIA ~ Noble (inert) Gases
 All gases
 Non-reactive
Group B Elements (Transition Elements)
 When compared to Group A elements; harder and more colourful, with higher boiling and melting
points
metalloids: located on both sides of the staircase line and have characteristics of metals and nonmetals
Matter has a well defined underlying structure composed of the following:
1. Atoms
 The smallest whole part of an element that is still representative of the element
 A neutral particle composed of a nucleus containing protons (p+) and neutrons, and electrons
(e-) outside the nucleus (the number of electrons equals the number of protons)
2. Ions
 A charged atom (The charge is caused by the transfer of an electron (or electrons) from one
atom to another)
 The metallic atom (which loses an electron) has a positive charge and is called a cation
- eg. Na+, Al3+
 The non-metallic atom (which gains an electron) has a negative charge and is called an anion
- eg. Clˉ, N3ˉ
 Other main features include:
- Atomic Number = Number of protons
- Number of protons = Number of electrons
- An energy level represents a specific value of energy of an electron and corresponds to a
general location
- Period number = Number of energy levels occupied by electrons
- The first three energy levels will have 2, 8, and 8 structures of electrons
NOTE: 2, 8, and 8 should be written as follows
started
-8e--
-8e-- -8e--
-2e-- -2e-- -2e-- Each lower energy level must be filled to its maximum before the next level is
- The electrons in the highest energy level are called valence electrons
- Group number = Number of valence electrons (one exception is helium) (Group A only)
- Max. number of electrons in each energy level = Max. number of atoms in each period
Energy Level Diagrams For Atoms
valence level: the outer-most energy level of an energy level diagram
NOTE: It is important to include atom when writing the name
 ex. Lithium atom (Students will be expected to format all energy level diagrams for atoms as
follows)
Valence Electrons (Valence Level):
- 1e-- 2e-Atomic Number:
3p+
Name:
Lithium atom
Symbol:
Li
Energy Level Diagrams For Ions
ion: a charged atom
 Formed when a metal loses electrons to form a positive ion (cation) or when non-metals gain
electrons to form a negative ion (anion)
 All atoms gain/lose electrons to become like the nearest noble gas (become stable)
When naming ions:
 Metal (cation) names: stay the same
 Non-metal (anion) names: change (last three letters become “ide”)
ex. Lithium ion (Students will be expected to format all energy level diagrams for ions as follows)
- 2e--
Valence Electrons (Valence Level):
3p+
Atomic Number:
Name:
Lithium ion
Symbol:
Li+
 ex. Fluoride ion (The atom Fluorine becomes the ion Fluoride)
- 8e-- 2e-9p+
Valence Electrons (Valence Level):
Atomic Number:
Name:
Fluoride ion
Fˉ
Symbol:
Isotopes
 Atomic number = Number of protons in the nucleus of an atom
 Atomic mass (mass number) = Sum of the protons and neutrons in the nucleus of an atom
isotopes: forms of an element that have the same number of protons but different numbers of
neutrons
Two Ways to Write Isotopes
 ex. Argon
Atomic mass (AM)
Atomic number (AN)
 ex.
40
18
Ar
Atomic Mass
argon-40
Atomic Mass
Retrieving Information About Isotopes
 Atomic mass is given in both naming forms
 Atomic number is either given or must be looked up on the Periodic Table
 Number of protons = Atomic number
 Number of electrons = Number of protons
 Number of neutrons = Atomic mass minus atomic number (n = AM – AN)
Download

chemnotes1.15 / Microsoft Office Word Document