Turning Points in Chemistry

Question 1

When investigating the atom Dalton followed these steps. Place them in the correct order:
Test the explanation
Suggest a different explanation if needed
Check the evidence
Ask a question
Test and check the evidence again
Suggest an explanation

Answer 1

Ask a question
Suggest an explanation
Test the explanation
Check the evidence
Suggest a different explanation if needed
Test and check the evidence again

Question 2

What is the name of the tiny particles that make up everything

Answer 2

Atoms

Question 3

Name the 3 subatomic particles in an atom

Answer 3

Electrons
Neutrons
Protons

Question 4

What charge does a neutron have?

Answer 4

No charge (Neutral)

Question 5

If an atom has 7 electrons how many protons does it have?

Answer 5

7 (no. of protons = no. of electrons)

Question 6

Which subatomic particles are found in the nucleus?

Answer 6

Neutrons

Protons

Question 7

In the gold foil experiment what did Rutherford ‘shoot’ at the gold foil

Answer 7

Positive alpha particles

Question 8

Which sub atomic particle was discovered through the gold foil experiment

Answer 8

Proton

Question 9

Why did the alpha particles bounce off the protons?

Answer 9

Like charges repel - Protons have positive charges

Question 10

If the majority of alpha particles went through the foil what does that suggest about atoms

Answer 10

They are mainly empty . The nucleus is compact/small

Question 11

What property was the first thing Mendeleev based the periodic table off

Answer 11

Atomic mass

Question 12

Mendeleev grouped elements based off what?

Answer 12

Physical properties

Formula of its compounds with hydrogen and oxygen

Question 13

Why did Mendeleev leave gaps in the periodic table

Answer 13

For elements he had been predicted but had not been discovered

Question 14

Rhenium is a catalyst. What is a catalyst?

Answer 14

A catalyst is something that speeds up chemical reactions but remains unchanged after the reaction

Question 15

What is a fossil?

Answer 15

Remains, traces or imprints of plants or animals

Question 16

Which rock type do fossils occur in

Answer 16

Sedimentary

Question 17

How is a fossil formed

Answer 17

Death and burial by sediments.
The fleshy parts rot away/dissolved/ are broken down by bacteria.
Rock forms around the skeleton and minerals replace the original skeleton forming a hard copy.
Rock around the fossil erodes and exposes the fossil.

Question 18

Why does fossils not form in igneous or metamorphic rock

Answer 18

magma, lava, heat and pressure would destroy remains

Question 19

Layers of sedimentary rock are called what?

Answer 19

Strata

Question 20

What is an index fossil

Answer 20

A fossil with a known age that can be used to identify the age of the strata

Question 21

Why were the cathode rays deflected in Thompson’s experiment?

Answer 21

Cathode rays have a negative charge. Electrons in the atom have a negative charge so deflected the rays as like charges repel

Question 22

What was the name of Thompson’s model of the atom

Answer 22

plum pudding model

Question 23

Why is it so important to the scientific community that scientists write their findings up in scientific journals?

Answer 23

so that they can check the results/ carry out the investigation themselves
allows repeats to be carried out many times, providing more accurate/ reliable results
allows scientific knowledge to develop/ other scientists may use the results to carry out new investigations

Question 24

How can the location of a fossil give an indication of its age?

Answer 24

Fossils are found in distinct layers/ strata of rock.
Different strata have different ages/ different strata correspond to different time periods/ lowest strata were formed earlier/ fossils in lower strata are older.
Only certain fossils are found in certain strata or time periods/ index fossils give the age of the strata and nearby fossils.

Question 25

Dalton suggested that there was space between particles. Think of an example that proves this.

Answer 25

Salt in water experiment. The water does not overflow when salt is added. If there was no space then the water would overflow straight away

A syringe containing air can be compressed.
The space is reduced when the particles are pushed together.
If there was no space it would not be able to be compressed

Question 26

Which subatomic particle is the smallest?

Answer 26

Electron