Chemistry2 7H Atoms, elements and compounds

Question 1

Gold, oxygen and sodium are examples of elements. What is an “element”?

Answer 1

Elements are substances made of only one type of atom. They cannot be broken down into anything smaller or simpler.

Question 2

Complete the sentence - All matter (stuff) is made up of tiny particles called ______.

Answer 2

All matter (stuff) is made up of tiny particles called ATOMS.

Question 3

What is the difference between an atom and a molecule?

Answer 3

An atom is a particle that is not chemically bonded to another. A molecule is made of two or more atoms chemically bonded (joined) together.

Question 4

What is the difference between a molecule and a compound?

Answer 4

A MOLECULE is made of two or more atoms chemically bonded (joined) together. The atoms can be the same e.g. O2 (oxygen). A COMPOUND is made of two or more different atoms bonded together e.g. CO2 (carbon dioxide) or MgO (magnesium oxide).

Question 5

What is A in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 5

A is a COMPOUND because it is a substance that contains two different elements bonded (joined) together. It is also a molecule because the atoms are joined together.

Question 6

What is B in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 6

B is a MIXTURE of two ELEMENTS. One of the ELEMENTS is a MOLECULE because its ATOMS are joined together.

Question 7

What is C in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 7

C is a MIXTURE of an ELEMENT and a COMPOUND.

It is a mixture because the substances can be separated.

Question 8

What is D in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 8

D is a COMPOUND because it is a substance made from three different types of ATOMS chemically BONDED together. The atoms cannot be SEPARATED.

Question 9

What is E in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 9

E is an ELEMENT because it is a substance made from only one type of ATOM.

E is also a MOLECULE because the atoms are chemically bonded (joined) together.

Question 10

What is F in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 10

F is an ELEMENT because it is a substance made from only one type of ATOM.

Question 11

What is G in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 11

G is a MIXTURE of two DIFFERENT compounds. They are COMPOUNDS because they contain different types of ATOMS BONDED together.

Question 12

What is H in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 12

H is an ELEMENT because it contains only one type of ATOM. H is a solid as its atoms are packed closely together.

Question 13

What is I in the picture below and why?

Choose words from this list in your answer - molecule, element, atom, compound, mixture, bonded or joined, separate, same, different.

Answer 13

I is a COMPOUND because it is a substance made from two different types of ATOMS chemically BONDED together. The atoms cannot be SEPARATED.

Question 14

Air is a mixture of gases. What gases are found in air?

Answer 14

Air is mainly nitrogen (78% ) and oxygen (21% ). The remaining 1% is made up mostly of argon, carbon dioxide and water vapour.

Question 15

What percentage of the air is oxygen?

Answer 15

The air is 21% oxygen.

Question 16

What gas makes up most of the air around us?

Answer 16

Nitrogen makes up 78% of the air around us. Oxygen makes up nearly all the rest (21%). The remaining 1% is is made up of argon, carbon dioxide and water vapour.