Question

1 - 5 density
the concept of density is about how close atoms and molecules are. if a substance is dense, its atoms or molecules are close together.
example: the dots below represent atoms.
in the first example we have 9 dots - 1 dot per square. there is a lot of space in between the dots (atoms). look at the square labeled “a”. there is only 1 dot in the square.
example 1
one dot (atom) in square a
in the second example we take the same 9 dots, but we put them all in one square. now there is not a lot of space between the dots (atoms). look at the square labeled “a”. now there are 9 dots in the square.
example 2
nine dots (atoms) in square a

1. how many total dots are in example 1? 9 how many in example 2? 9
2. in which example are the dots (atoms) closer together? example #
3. in which example do the dots take up more space (more volume)? #
4. which example shows a greater density in square a? #

to calculate density we need to know how many dots (atoms) are in a substance and how much space the dots (atoms) take up.

1. which choice below is a measure of how many atoms/molecules are in a substance (circle it)?

weight mass volume

1. which choice below is a measure of how much space an object takes up (circle it)?

weight mass volume

Explanation:

Step1: Count dots in examples

Both example 1 and example 2 have 9 dots as stated in the problem - text.

Step2: Compare dot - closeness

In example 2, the 9 dots are in one square while in example 1, 9 dots are spread over multiple squares. So dots are closer together in example 2.

Step3: Compare space taken up

In example 1, dots are spread out, so they take up more space (volume).

Step4: Compare density

Density is mass/volume. In square A, example 2 has 9 dots and example 1 has 1 dot. So example 2 has greater density in square A.

Step5: Identify measure of atoms/molecules

Mass is a measure of how many atoms/molecules are in a substance.

Step6: Identify measure of space

Volume is a measure of how much space an object takes up.

Answer:

1. 9; 9
2. 2
3. 1
4. 2
5. mass
6. volume