1. How Are Elements Classified?
Scientists classify elements into groups based on their properties.
A physical property is a characteristic of a substance that can be observed without changing the substance into another substance. Color, hardness, and shine (or luster) are examples.
An element’s chemical properties determine how the element combines with others to form compounds. Burning, tarnishing, and rusting are examples.
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2. Scientists have organized the elements according to their properties into the periodic table.
Three groups of elements are metals, nonmetals, and metalloids. Elements on the left side of table, except hydrogen, are metals. Elements on the right side of the table are nonmetals. The metalloids are along each side of the zigzag line between the metals and nonmetals.

3. What Are The Physical Properties of Metals?
Metals are often shiny, malleable, ductile, and can conduct electricity.
A malleable material is one that can be rolled into flat sheets.
A ductile material is one that can be pulled out into a long wire.
Conductivity is the ability of an object to transfer heat or electricity to another object. Most metals are good conductors.
Most metals are solid at room temperature.
1. Explain What is conductivity?

4. What Are The Physical Properties of Nonmetals?
In general, the physical properties of nonmetals are the opposite of those of metals.
Solid nonmetals are dull, meaning not shiny. They are brittle, meaning not malleable or ductile.
Nonmetals are poor conductors of electricity.
Ten of the 16 nonmetals are gases at room temperature.
2. Form Operational Definitions Based on the characteristics listed above, how would you define a nonmetal?

5. What Are The Physical Properties of Metalloids?
The metalloids have some characteristics of both metals and nonmetals.
Metalloids are solid at room temperature.
Metalloids are brittle and hard.
Metalloids vary in how well they conduct electricity.
3. Compare Which properties of metalloids are similar to those of metals? Which are similar to those of nonmetals?