Embedded Files
INTRODUCTION
INTRODUCTION
We live in a world that contains a vast number of different materials Yet the components of all these many materials can be separated into about 115 basic building blocks called elements.
There are about 90 naturally occurring elements, and another 25 synthetic elements. Based on their properties, all of the elements cab be divided into three classes: metals, non-metals and metalloids.
periodic table
periodic table
Periods and Families:
Periods and Families:
You will be using the periodic table of the elements for the remainder of these, and the following, unit. In order to become more familiar with its organization, read page 31.
Define the following terms in your Science notebook:
Define the following terms in your Science notebook:
period
group (family)
alkali metals
alkaline-earth metals
noble gases
halogens
Atomic theory
Atomic theory
An atom is the smallest part of an element that still has the properties of the element.
Subatomic particles
Subatomic particles
Pages 33-34
Proton (positively charged particles)
Neutron (neutral particles)
Electrons (negatively charged particles)
Electrons occupy most of the volume of an atom. Most of the mass is in the nucleus.
energy levels
energy levels
Pages 32- 33
Electrons take up most of the volume of an atom (over 99.9%), and they occupy specific energy levels.
An energy level can be thought of as a region of space near the nucleus that may be empty of may contain electrons.
Electrons in energy levels closest to the nucleus:
have the lowest energy
electrons most tightly held in the atom because they are closest to the positively charged nucleus.
Electrons in energy levels farther away from the nucleus:
have more energy
not as tightly bound
An energy level can be:
empty
partly filled
completely filled
ATOMIC NUMBER, MASS NUMBER AND ATOMIC MOLAR MASS
ATOMIC NUMBER, MASS NUMBER AND ATOMIC MOLAR MASS
Pages 32-33
elements combine to form compounds
elements combine to form compounds
Page 36-38
Valence Electrons: the electrons in the outer energy level; these electrons participate in bonding
•Elements in the same family have the same number of valence electrons = similar chemical properties
Octet Rule: atoms bond in such a way as to have 8 electrons in their valence energy level
Fluorine has seven valance electrons; neon has eight valence electrons; and magnesium has two valence electrons. Using the octet rule, we can determine that fluorine gains one more electron, neon doe not gain or loose any; and magnesium loses two to join other elements.
FORMATION OF IONS AND ISOTOPES
FORMATION OF IONS AND ISOTOPES
Pages 33-34
learning activities
learning activities
Click here to view answers
2. Answer the Check and Reflect questions #1 - 12 on page 39.
Next: You are now ready to move on to complete section A2.2
Page updated
Report abuse