Topic 1.1- Key concepts

Question 1

How has the dalton model changes over time?

Answer 1

• Dalton believed atoms couldn’t be broken down
• Plum Pudding: Thompsons experiments with cathode rays proved negatively charged electrons
  -Nuclear model: Rutherford gold foil experiment discovered a positively charged nucleus and is mostly empty space

Question 2

Why do atoms contain the same number of electrons and protons?

Answer 2

For it to have neutral charge

Question 3

How much smaller is the nucleus of an atom compared to the size of the atom?

Answer 3

100,000 times smaller

Question 4

What is the mass of a neutron and proton?

Answer 4

1

Question 5

What is the mass of an electron?

Answer 5

1/1837

Question 6

what does mass of an atom mean?

Answer 6

the sum of individual particles (neutrons and protons)

Question 7

What is an isotope?

Answer 7

-Same electrons and protons
-Different number of neutrons
-Affects weight

Question 8

What is the atomic number?

Answer 8

The number of protons

Question 9

How is the periodic table organised?

Answer 9

Increasing atomic number

Question 10

How to calculate relative atomic mass?

Answer 10

          Total abundance

Question 11

How big is an atom

Answer 11

0.1 nm radius

Question 12

How did Mendeleev arranged the elements?

Answer 12

Rows by increasing atomic mass

Question 13

How was Mendeleev able to predict the existence and properties of new substances?

Answer 13

• Noticed every eighth element had same properties as the first, made rows of seven
• Left gaps when atoms didn’t fit in a group

Question 14

What was wrong about Mendeleev’s organisation?

Answer 14

Atomic mass didn’t take into account:
-Relative atomic mass
-Isotopes

Question 15

What are the rows called? And what do these mean?

Answer 15

Periods, number of rings/orbitals.