6 th Grade Science 2010-2011
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements, Compounds, and Mixtures
What Do You Think?
How is an element different from a compound?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Answer
An element is made up of only one pure substance, and a compound is composed of two or more elements that are chemically combined.
© Fall 2005, Pflugerville ISD, 7th Grade
Gold
Water http://www.worldofrockhounds.com/huge-gold-nugget-sm.JPG
http://www.nbmg.unr.edu/slides/water/5.htm
Unit 1

Elements
An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
A pure substance is a substance in which every particle of that element is the same.
– Example: Every particle in a 5g gold nugget is like every other particle of gold, no matter where they are found.
http://www.libertarian.nl/NL/archives/01-gold-bar.jpg
Unit 1 © Fall 2005, Pflugerville ISD, 7th Grade

Elements
The Periodic Table of Elements is arranged according to these properties.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Every element has a unique set of properties.
Some physical properties that are used to classify elements are boiling point, melting point, color, and density.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Chemical properties used to separate elements from each other include reactivity with acids, or reactivity with oxygen.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements Are Grouped
Some elements are shiny, and can conduct thermal energy.
They are all grouped together on the left hand side of the
Periodic Table. They are called metals . Not all metals are exactly alike, but they do have some properties in common.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Elements Can Be Identified By
Categories
If you know the category, you know the properties.
1. Share with your class how
CDs can be classified by categories?
© Fall 2005, Pflugerville ISD, 7th Grade
2. How can dogs be classified by categories?
Unit 1

Elements
• Metals
• Nonmetals
• Metalloids
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Metals
Metals are elements that are usually shiny and good conductors of electricity and heat.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Metals
Metals are also malleable (can be hammered into thin
sheets).
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
• Metals are ductile , or can be drawn into thin wires.
• Metals are located to the left of the “zig zag line” on the Periodic Table.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
• Examples: Iron (Fe) and
Copper (Cu).
http://www.flamo.net/crystals/iron.jpg
© Fall 2005, Pflugerville ISD, 7th Grade http://resourcescommittee.house.gov/subcommittees/emr/usgsweb/materials/copper.html
Unit 1

Elements
Click below to see properties of Metals.
© Fall 2005, Pflugerville ISD, 7th Grade http://www5.unitedstreaming.com/index.cfm
Unit 1

Elements
Nonmetals
• Usually dull and poor conductors of heat and electric current.
• Tend to be brittle and unmalleable.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Nonmetals
• Nonmetals are located to the right of the “zig zag line” on the Periodic Table.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Nonmetals
• Examples: Neon (Ne) and
Carbon (C) www.neonstreet.com/ sign2.html
© Fall 2005, Pflugerville ISD, 7th Grade reluctant-messenger.com/ diamond_sutra.htm
Unit 1

Elements
Click below to see properties of Nonmetals
© Fall 2005, Pflugerville ISD, 7th Grade http://www5.unitedstreaming.com/index.cfm
Unit 1

Elements
Metalloids
Share properties of both metals and nonmetals.
• Can be shiny or dull.
• Somewhat malleable and ductile.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
• Metalloids touch the “zig zag line” on the Periodic Table.
• Examples:
Silicon (Si) Arsenic (As).
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements
Click below to see properties of metalloids.
© Fall 2005, Pflugerville ISD, 7th Grade http://www5.unitedstreaming.com/index.cfm
Unit 1

Let’s Review!
- 1 -
Describe some physical properties of the element iron.
http://neil.fraser.name/news/2004/05/22/
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Answer
Physical properties include:
1. Melting Point: 1535 °C
2. Density: 7.9 g/cm 3
3. Iron has the ability to conduct heat and electrical current.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Let’s Review
- 2 -
What is an example of a metal that is very malleable, shiny, and is used often in kitchens?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Answer
Aluminum Foil
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
What Do You Think?
What do salt, sugar, baking soda, and water have in common?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
A compound is a pure substance composed of two or more elements that are chemically combined.
Familiar Compound
Compound
Table Salt
Water
Sugar
Elements Combined
Sodium and Chlorine
Hydrogen and Oxygen
Carbon, Hydrogen, and Oxygen
Carbon Dioxide Carbon and Oxygen
Baking Soda Sodium, Hydrogen, Carbon, and Oxygen
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
Properties of Compounds
• Compounds, like elements, can be identified by their own physical and chemical properties.
• What are some examples of physical and chemical properties?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
Each compound has different properties than the elements that make them up.
Water Hydrogen Oxygen
Melting Point
Boiling Point
0
°C
100 °C
Density 1.0 g/cm 3
State at Room Temperature
Liquid
-259.14
°C
-252.87 °C
0.08988 g/cm 3
Gas
-218.4
°C
-183.0 °C
1.429 g/cm 3
Gas
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
Compounds are
Composed of
Elements.
The compound Water is composed of Hydrogen and Oxygen chemically bonded together.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
Compounds are Composed of Elements.
• The compound Ammonium is composed of Nitrogen and
Hydrogen chemically bonded together.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
Click below to see a video clip of sodium metal and chlorine gas being combined.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Let’s Review!
- 1 -
What is the difference between an element and a compound?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Answer
• An element is a pure substance that
cannot be separated into simpler means by physical or chemical means.
• A compound is a pure substance composed of two or more elements that
can be broken into simpler substances by a chemical change.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Compounds
Make a Venn diagram comparing and contrasting elements and compounds.
Elements Compounds
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements, Compounds, and
Mixtures
Pre-AP Extensions for Chapter 2
• Mixtures are combinations of two or more elements that are not chemically combined.
• Mixtures can be separated into 2 types: homogenous mixtures and heterogenous mixtures .
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements, Compounds, and
Mixtures
Homogenous Mixtures
• A homogenous mixture is a mixture of two or more substances that is completely uniform in composition.
• Homogenous mixtures can be separated by physical means, but it is often difficult to do.
• Examples include salt water, kool aid, and air.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements, Compounds, and
Mixtures
Heterogenous Mixtures
• A heterogenous mixture consists of many different items, which are often not easily sorted or separated, though they are clearly distinct.
• Examples include oil and water mixed together, sand or gravel, and even chocolate chip cookies!
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Elements, Compounds, and
Mixtures
• Percent Calculations in a Mixture
• Chromatography Mixtures Lab
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
What Do You Think?
How do scientists use physical properties to arrange elements on the periodic table?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Dimitri Mendeleev discovered a pattern to the elements in the periodic table in
1869.
www.astrosurf.org/lombry/ quantique-histoire.htm
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
He simply wrote the names of all of the elements on cards, along with some of their properties.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
• Mendeleev tried arranging his cards based on different properties like color, density, melting point, and atomic mass.
• He found that by arranging the elements by increasing atomic mass, he found many other properties that fit a pattern.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Mendeleev found that by arranging the elements by increasing atomic mass, similar physical and chemical properties repeated in every 8 th element.
This is called periodic , or having a regular, repeating pattern.
Can you think of anything else that is periodic?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Let’s Review!
- 1 -
Why was Mendeleev so important in the study of the periodic table?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Answer
• Mendeleev was responsible for arranging the periodic table by increasing atomic mass.
• This arrangement organizes the table making it easier for us to use.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
What Do You Think?
How do scientists use physical properties to arrange elements on the periodic table?
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Elements are classified on the periodic table based on their properties.
• Like we learned in Chapter 2, we classify them as metals, nonmetals, and metalloids.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Metals
Remember that
metals are shiny, ductile, malleable, and are good conductors of thermal energy and electrical current.
http://shawnee.noacsc.org/highschool/departments/teachers/pages/mikel/periodictable.html
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Metals
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Physical Properties of Metals
© Fall 2005, Pflugerville ISD, 7th Grade
Go.hrw.com
Unit 1

Introduction to the Periodic Table
Chemical Properties of Metals
© Fall 2005, Pflugerville ISD, 7th Grade
Go.hrw.com
Unit 1

Introduction to the Periodic Table
Nonmetals
Remember also that nonmetals are not shiny and are poor conductors of thermal energy and electric current.
http://shawnee.noacsc.org/highschool/departments/teachers/pages/mikel/periodictable.html
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Nonmetals http://shawnee.noacsc.org/highschool/departments/teachers/pages/mikel/periodictable.html
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 1

Introduction to the Periodic Table
Physical and Chemical Properties of Nonmetals
© Fall 2005, Pflugerville ISD, 7th Grade
Go.hrw.com
Unit 1

Introduction to the Periodic Table
Metalloids are elements that have properties of both metals and nonmetals.
Metalloids http://shawnee.noacsc.org/highschool/departments/teachers/pages/mikel/periodictable.html
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Metalloids
Metalloids border the
“zig zag” line on the periodic table.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Physical and Chemical Properties of Metalloids
© Fall 2005, Pflugerville ISD, 7th Grade
Go.hrw.com
Unit 1

Let’s Review!
- 1 -
Use the properties of metalloids to explain their position on the periodic table.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Answer
• Metalloids are located between metals and nonmetals because they have properties in between metal and nonmetals.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Pre-AP Extensions for Chapter 3
• There are trends in Metallic and
Nonmetallic Character that we can see on the periodic table.
• Metallic character is strongest for the elements in the leftmost part of the periodic table, and tends to decrease as we move to the right in any period.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
• Within any group of elements
(columns), the metallic character increases from top to bottom . This general trend is not necessarily observed with the transition metals.
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1

Introduction to the Periodic Table
Pre-AP Extensions for Chapter 3 http://wine1.sb.fsu.edu/chm1045/notes/Periodic/Metals/Period06.htm
© Fall 2005, Pflugerville ISD, 7th Grade Unit 1