Science 5.3

Atoms and Molecules

What is the difference between atoms and molecules? It is actually pretty simple. Molecules are made up of atoms. Each element on the periodic table of elements is made up of one single type of atom. Molecules are formed when atoms bond. Different types of atoms can form together to make a molecule. Two or more of the same type of atom can also be bonded to make a molecule. For example, H is the symbol for hydrogen and O is the symbol for oxygen. Water is made up of both hydrogen and oxygen. H2O is the symbol for water. Two hydrogen atoms and one oxygen atom are bonded together to create a water molecule. Oxygen gas is made up of two oxygen atoms bonded together. O2 is the symbol for an oxygen molecule. With so many elements, imagine all the combinations of atoms that have been researched and have yet to be researched. Chemistry is very complicated because there are so many different combinations.

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1. Water molecules are made up of

a. any two atoms bonded together.

b. two hydrogen atoms and one oxygen atom.

c. atoms of only one type of element bonded together.

d. two oxygen atoms.

2. Why does the author describe the atoms that make up water?

a. to give an example of a specific molecule

b. to show how liquids are different from solids

c. to explain why water is so abundant

d. to illustrate how simple chemistry is

3. Can a single atom be considered a molecule?

a. only if the atom is found in water

b. no, it takes two or more atoms bonded to create a molecule

c. only if it is an oxygen atom floating in the air

d. yes, all atoms are made up of many different molecules

Lesson 2.3: Physical Science – Chemical Properties

4. What is the main idea of this paragraph?

a. Bonded atoms make up molecules.

b. Atoms and molecules are unrelated to each other.

c. Water is the most common type of molecule.

d. Oxygen and hydrogen are necessary for molecules.

5. What makes up a molecule of oxygen gas?

7. Explain why understanding bonding is important for understanding molecules.

8. The question below is an incomplete sentence. Choose the answer that best

completes the sentence.

Molecules can be made up of two atoms of the same element; __________________ ,

oxygen gas is made up only of oxygen atoms.

a. for example

b. most importantly

c. on the other hand

d. therefore

9. Read the following sentence.

Two hydrogen atoms and one oxygen atom create a water molecule by bonding

together.

Answer the questions below based on the information provided in the sentence you

just read. One of the questions has already been answered for you.

1. What?

Two hydrogen atoms and one oxygen atom

2. What do hydrogen and oxygen atoms do?

__________________________________________

2. How?

__________________________________________

10. Challenge: Summarize (use your own words) the main idea of the paragraph.