Elements and Compounds Lesson 2: What Are Metals?

San Francisco’s City Hall Dome The dome on San Francisco’s City Hall is 307.5 feet high. This is 14 inches higher than the done of the Capitol Building in Washington, D.C. The dome was refinished when its old finish peeled off. Gold leaf was applied over a special paint to protect it.

California State Standards: 1.c) Students know metals have properties in common, such as high electrical and thermal conductivity. Some metals, such as aluminum (Al), iron (Fe), nickel (Ni), copper (Cu), silver (Ag), and gold (Au), are pure elements; others, such as steel and brass, are composed of a combination of elemental metals. 1.e) Students know scientists have developed instruments that can create discrete images of atoms and molecules that show that the atoms and molecules often occur in well-ordered arrays.

Valuable Vocabulary Metal- A substance that transfers heat and electricity well and is malleable.

Valuable Vocabulary Nonmetal- a substance that does not transfer heat and electricity well and is not malleable. The prefix non- means “not.”

Valuable Vocabulary Malleable- easy to shape or to form. Malleable is derived from the Latin term malleus meaning “hammer.”

Valuable Vocabulary Metalloid- A substance that has some of the properties of a metal and some of the properties of a nonmetal.

Valuable Vocabulary Alloy- a solid solution made by combining metals or a metal and nonmetal.

Metals and Nonmetals Metals conduct heat and electricity well and are malleable whereas nonmetals do not conduct heat and electricity well.

Metals and Nonmetals Imagine you are at a park on a hot, summer day. You notice a tall, metal slide positioned next the swings. Would you go down the slide? Why or why not?

Metals and Nonmetals Some people would not go down the metal slide because it was probably too hot due to the sunlight. A metal is a substance that is a good conductor of heat and electricity. Metals heat up quickly, and electricity passes through them easily.

Metals and Nonmetals About 75% of the elements on the periodic table are metals. Metals are located on the left side, with the exception of hydrogen, and the middle of the periodic table.

Metals and Nonmetals Hydrogen and the elements found on the right side of the periodic table are nonmetals. Nonmetals are substances that do not have the same properties as metals. They do not conduct heat and electricity well. Example: Plastic

Metals and Nonmetals On a hot, summer day a metal slide feels much hotter than a plastic slide. Plastic- a substance made of nonmetals- does not conduct heat or electricity very well.

Metals and Nonmetals Most metals are silver or gray in color. Some substances pretend to look like a metal. These substances are called metallic- they reflect light and are often shiny. Examples: Gold, silver, and new pennies.

Metals and Nonmetals

Metals and Nonmetals Other than being good conductors of heat and electricity, metals are malleable. They are easy to shape or form; they can be hammered or rolled into very thin sheets. The San Francisco City Hall dome is less than one millimeter thick!

Metals and Nonmetals We all use metals in our daily lives! Gold was most likely the first metal used by humans because it does not rust and is often found in nature as a pure element. As we learned to work with metals, other forms of technology improved as well.

Metals and Nonmetals

Show What You Know How can you tell if a substance is a metal?

Show What You Know How can you tell if a substance is a metal? Metals conduct heat and electricity well. They are malleable and reflect light.

Show What You Know Where are metals and nonmetals found on the periodic table?

Show What You Know Where are metals and nonmetals found on the periodic table? Metals are found on the left side and middle of the periodic table. Nonmetals are found on the right side of the periodic table.

Show What You Know What does the term “malleable” mean?

Show What You Know What does the term “malleable” mean? Malleable means easy to shape or form.

Summary Time! Write a summary about what you learned today. Be sure to: Use complete sentences Use proper punctuation Answer in paragraph form

Properties of Metals Metals have the same properties: they conduct heat and electricity well, they are malleable, and they have melting and boiling points.

Properties of Metals Think about each column in the periodic table. What do we know about these columns?

Properties of Metals

Properties of Metals We know that all elements in the same column of the periodic table have similar physical properties. Each column is known as a “family.” Like a real family, these elements are related. For example, lithium and other metals in the first column are the most active metals.

Properties of Metals Another physical property of metals include their melting and boiling points.

Properties of Metals Another physical property of metals include their melting and boiling points For example, when mercury is heated or cooled, it expands or shrinks evenly.

Properties of Metals Metals are in our every day lives! Since metals are good conductors of heat, many cooking pans are made of metal. They have a high thermal conductivity. The handles of pans are covered with plastic or wood because nonmetals do not conduct heat very well.

Properties of Metals Another important use of metals is in electrical wiring. On the outside of a cord of an appliance, there is rubber or plastic. Inside the cord is a metal wire, usually copper. Copper allows electricity to pass through easily, meaning they have high electrical conductivity.

Properties of Metals The rubber or plastic on the cord of the appliance is known as an insulator. Materials that do not conduct electricity or heat well are called insulators. They prevent us from getting shocked!

Properties of Metals Different metals have different densities. Aluminum and titanium are less dense than others, therefore, they are very light. These metals are often used in airplanes and other objects in which weight is important.

Show What You Know Explain how the columns in the periodic table are related?

Show What You Know Explain how the columns in the periodic table are related? The columns in the periodic table have similar physical properties.

Show What You Know What elements have properties similar to those of the element calcium?

Show What You Know What elements have properties similar to those of the element calcium? The elements that have similar properties to calcium are berylium, magnesium, strontium, barium, and radium.

Show What You Know What properties do aluminum, iron, and copper have in common?

Show What You Know What properties do aluminum, iron, and copper have in common? Aluminum, iron, and copper all conduct heat and electricity and are malleable.

Show What You Know What are some physical properties of metals?

Show What You Know What are some physical properties of metals? Some physical properties of metals are their melting and boiling points, malleability, and conductivity of heat and electricity.

Show What You Know What is the material that does not conduct electricity or heat called?

Show What You Know What is the material that does not conduct electricity or heat called? The material that does not conduct electricity or heat is called an insulator.

Show What You Know How do the properties of metals affect the ways they are used?

Show What You Know How do the properties of metals affect the ways they are used? Metals are used in pans because they are good conductors of heat. They are used in wires because they conduct electricity. They can be shaped in different objects. The less dense metals are used in airplanes.

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Alloys and Metalloids The properties needed for a particular use of an alloy determine the elements that go into it.

Alloys and Metalloids As we learned in the previous sections, we use metals in our everyday lives. Imagine you are sitting at the dinner table, eating a big, juicy steak, steamy mashed potatoes, and a fresh, green salad. When eating this delicious meal, you would use forks or spoons made of stainless steel.

Alloys and Metalloids The stainless steel that is used to make the forks and spoons is an alloy. An alloy is a solid solution made by combining metals or a metal with a nonmetal. The word alloy comes from the Latin word ad, meaning “to” and ligare, meaning “to bind.” Put together, the words mean “to bind to.”

Alloys and Metalloids An alloy contains properties that are different from the elements that the alloy contains. For example, iron is the main metal in many steel alloys. Iron is not very hard, but when it is made into steel by adding carbon, it becomes much stronger.

Alloys and Metalloids There are many different forms of steel. High-carbon steel is strong and flexible, which is why it is used for wire springs. Low-carbon steel can be formed into shapes, such as gas tanks.

Alloys and Metalloids Stainless steel does not rust, and it will not combine with the chemicals in food. There are some stainless steels that do not contain iron. You can use a magnet to see if your forks and spoons contain iron.

Alloys and Metalloids The first alloys made were different kinds of bronze. Bronze is made by combing tin and copper, which is harder, stronger, and less likely to corrode than copper. Corrode means “to break materials down by combining with things like oxygen.”

Alloys and Metalloids Many large statues are made out of bronze because they can withstand harsh weather conditions without corroding. Ship propellers are made of bronze because it resists corrosion by sea water. Another form of bronze contains aluminum that does not cause sparks when it is hit.

Alloys and Metalloids

Alloys and Metalloids Another type of element on the periodic table is the metalloids. Metalloids are elements that have some properties of metals and some of nonmetals. The suffix –oid means “like” or “resembling.” They are also called semimetals.

Alloys and Metalloids An example of a metalloid is silicon- it looks shiny, but it isn’t as strong as a metal. It breaks down when you hit it with a hammer. It conducts electricity, but not as well as copper or silver, so the flow of electricity can be easily controlled.

Alloys and Metalloids Elements that can conduct electricity but can be easily controlled are called semiconductors. These elements are used in computers and portable devices such as music players.

Show What You Know In your own words, explain what an alloy is.

Show What You Know In your own words, explain what an alloy is. An alloy is a solid solution that is made by combining either metal with metal or metals with nonmetals.

Show What You Know If an alloy is a solution of a solid dissolved in a solid, how might you make such a solution?

Show What You Know If an alloy is a solution of a solid dissolved in a solid, how might you make such a solution? Melt the two solids and mix them together. Then let the solution cool off to get a solid again.

Show What You Know What is the advantage of adding carbon to iron?

Show What You Know What is the advantage of adding carbon to iron? It makes the resulting steel stronger.

Show What You Know If you were building a large statue of your face that was going to be placed outside, in your front yard, which alloy would you use- bronze or copper? Why?

Show What You Know If you were building a large statue of your face that was going to be placed outside, in your front yard, which alloy would you use- bronze or copper? Why? If you were going to make a statue of your face, you would want to use bronze because it resists corrosion and is much harder and stronger than copper.

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Seeing Metal Atoms By understanding how atoms join together, it helps scientists develop new materials and control the properties of these materials.

Seeing Metal Atoms As we learned in lesson 1, atoms are extremely small. If you joined 20 million large atoms placed side by side, it would only measure one centimeter. So how can scientists see something so small?

Seeing Metal Atoms In the 1930s, scientists built an electron microscope that could magnify an object more than 50,000 times. This microscope used a stream of electrons to produce images of objects. They could see objects, such as parts of cells, in great detail.

Seeing Metal Atoms Only 50 years later, in 1980, a new type of microscope gave scientists the capability to look at atoms. A scanning tunneling microscope, or STM, uses a probe to examine the surface of a material.

Seeing Metal Atoms The STM produces an image based on how many electrons move from each part of the surface to the probe. They could see atoms in solids that were arranged in specific patterns.

Seeing Metal Atoms With an STM, scientists can watch atoms form natural crystals and arrays. An array is a pattern of atoms. Sometimes, there are missing pieces or flaws in these well-ordered arrays.

Seeing Metal Atoms

Seeing Metal Atoms This technology may become very helpful to people. Today, scientists can check materials for flaws before the materials are used.

Seeing Metal Atoms Scientists can also use STMs to observe molecules. By doing so, they learn why certain elements will and will not join together. This understanding helps improve all kinds of electronic devices.

Show What You Know Why do scientists want to be able to see atoms?

Show What You Know Why do scientists want to be able to see atoms? By understanding how atoms join together, scientists are able to develop new materials and control the properties of materials.

Show What You Know Why would scientists want to be able to move atoms around?

Show What You Know Why would scientists want to be able to move atoms around? Scientists would want to be able to move atoms in hopes to make new materials.

Show What You Know What would you look for if you were looking for a flaw using an STM?

Show What You Know What would you look for if you were looking for a flaw using an STM? If you were looking for a flaw using an STM, you would look for missing atoms, atoms that looked different from the others, or atoms that weren’t lined up like the rest.

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