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.