Introducing Elements, Compounds and Mixtures

Sodium and chlorine chemically mixed form -

The periodic table lists the number of known what?

• Compounds

• Mixtures

• Elements

• Alkalis

The number of elements in the periodic table is ____ .

Uranus and Neptune are mainly made of hydrogen, helium, methane and water. Which of them are compounds?

• Hydrogen

• Methane

• Water

• Helium

The San Francisco region is called the ____ Valley because of the high presence of ____ , used to make transistors. It is famous as a tech hub.

• silicon

• nickel

• tungsten

• silver

Higher Order Thinking Skills

In an electric bulb, we usually pump gases like krypton or argon to form a layer around the filament and not allow air as a whole inside. Why? (Think about the dangers of allowing air as a whole in)

• The air conducts electricity and will give us electric shock, but pure krypton and argon prevent it from reaching.

• Krypton and argon is abundant in the atmosphere and cheap, so people just use them.

• They are noble gases, which means that they have low reactivity rates, as a result preventing a fore from happening.

• It conducts heat, so that the bulb makes you warm and happy and can be used as a portable heater.

Who was John Dalton?

• A scientist from England

• An archaeologist from the United States

• A rich businessperson from Kenya

• An astronomer from India

Which of the following are points of Dalton’s atomic theory?

• All matter is made of atoms. Atoms are indivisible and indestructible.

• Elements are only found in the Solar System.

• Compounds are formed by a combination of two or more different kinds of atoms.

• A chemical reaction is a rearrangement of atoms.

• All compounds are conductors of electricity.

What are the components of an atom

• Protons

• Megatrons

• Electrons

• Neutrons

• Positrons

What element has only one proton and one electron?

• Chlorine (Cl)

• Hydrogen (H)

• Potassium (K)

• Uranium (U)