Transcript Activity 15: Families of Elements

Activity 15:
Families of Elements
Read B-19
• Challenge Question:
How can elements be grouped based on
their physical and chemical properties?
Unit B Vocabulary
• Atom
– The basic structural unit of matter. Made
up of Protons, Neutrons, and Electrons.
Each element has a particular type of
atom.
• Atomic Mass
– The average mass of the atom of an
element (protons + neutrons). It’s also
known as atomic weight.
Unit B Vocabulary
• Element
– A substance that cannot be broken down by
any normal chemical means, such as heating,
reacting them with acids or other chemicals, or
exposing them to electrical currents.
• Family (of elements)
– A grouping of elements based on similar
chemical properties. Columns in the periodic
table.
Unit B Vocabulary
• Metal
-Category of elements that usually have a shiny
surface, are generally good conductors of heat and
electricity, and can be melted or fused, hammered
into thin sheets, or drawn into wires.
• Periodic Table
– An arrangement of the elements according to their
atomic numbers so that elements with similar
properties are in the same column.
In Activity 14…
• You grouped materials and sorted them into
categories based on their properties.
• The efforts of scientists and philosophers to
classify matter go far back in history.
• More than 2,000 years ago, the Greeks
introduced the idea that there were some
basic building blocks of matter, called
elements.
Elements are the building blocks
of matter
• Today’s scientists know that there are 90
naturally occurring elements.
• Each visible sample of an element is made
of many billions of small particles called
atoms.
• Each kind of element is made of a particular
kind of atom.
• One way in which the atoms vary is in their
mass.
Element Samples
• In Activity 14, you tested four elements:
–
–
–
–
Aluminum
Iron
Copper
Carbon
• These were among some of the first elements
early scientists identified.
• More Samples
• In this activity, you will view data on 14 elements
and investigate how these can be divided into
subgroups based on their properties.
Information on Element Cards
• Transparency 15.1
• One- or two-letter symbol and name
• Two physical properties
–
–
–
–
Metal or Non-Metal
Solid, Liquid, or Gas at room temperature
Color of the most common form(s) of the element
Atomic mass refers to the mass of one atom
• Chemical properties.
– Reactivity: how likely the element react with other
elements.
– Number of bonds to hydrogen. (H2O)
Procedure:
Follow procedure on pages B-20 to B-21
Data/Evidence:
Procedure #4
Group
Name:
Common
Properties
Data/Evidence:
Procedure #9
Family
Name
Similar
Properties
Elements
in order of
increasing
atomic
mass
Element Family Card
• Scientists look for patterns in their
observations and use the same data you
used plus additional data to categorize the
elements into groups called families.
• You need to know the family names and
their properties.
– Alkali Metals
– Alkaline Earthmetals
– Halogens
– Noble gases
Family of Elements
• Alkali Metals
–
–
–
–
(H)
Li
Na
K
• Alkaline Earth Metals
– Be
– Mg
– Ca
• Halogens
–F
– Cl
– Br
• Noble Gases
–
–
–
–
He
Ne
Ar
Kr
Periodic Table
• The cards show only 14 of the more than 100
known elements.
• Scientists have taken a similar approach to classify
and organize all of the elements onto a table called
the Periodic Table of the Elements.
• The categories for the Element Family Cards are
four of the accepted scientific classifications.
• Student Sheet 16.1 - Families
• Noble (or Inert) gases refers to the fact that these
elements only very rarely react.
Periodic Table
• Organizes a large number of elements into
columns and rows and provides atomic numbers
and atomic masses for each (we will talk about
this more later).
• Systems for classification and organization,
– Scientists organize and make sense of vast amounts of
data
– Scientists from all over the world can communicate with
each other and exchange information in a common
scientific vocabulary.
– As new elements have been discovered, new rows have
been added and other modifications have been made.