Where metals come from 132
Metals are most often found in rocks on the Earth. Metals are sometimes found in sand because sand is rock that is worn away over a long time. Most often metals are in the form of ore. Ores are a kind of rock with very small pieces of metal inside. To get the metal out, the ore is crushed and sometimes heated or chemicals are used. The places where people get metals from the Earth are called mines. People sometimes dig mines making big holes in the ground, to get at the ore. Many things that are made of metals may, in fact, be made of mixtures of at least one metal with either other metals, or with non-metals. These mixtures are called alloys. Some common alloys are:
Steel (iron and carbon) (Carbon is a non-metal)
Brass (copper and zinc)
Bronze ( copper and tin)
People first began making things from metal over 6000 years ago, when they discovered how to get copper from its ore. They then learned how to make a harder alloy, bronze, by adding tin to the copper. About 3000 years ago, they discovered iron. By adding small amounts of carbon to iron, they found that they could make a particularly useful alloy – steel. Iron and the large family of iron alloys called steel are the most common of the commercial metals. Iron melts at 2,777 F and boils at 4,442 f. Small addition of carbon reduces the melting point.
Ore – руда crush – вижимати mine - шахта, копальня brass – жовта мідь cooper – мідь tin – олово
Ex.17. Agree or disagree with the following statements:
a) Metals are most often found under the ground.
b) The places where people get metals from the Earth are called caves.
c) People first began making things from metal over 6000 years ago.
d) Carbon and the large family of iron alloys called steel are the most common of the commercial metals.
e) Small addition of carbon reduces the melting point.
Ex. 18. Answer the following questions:
1. Where are metals found?
2. What do we call places where metals are obtained?
3. What is alloy?
4. Why did people begin to make things from metal?
5. What do we call iron and the large family of iron alloys ?