Radioactivity- Atoms

Question 1

What is the first model of the atom and who discovered it?

Answer 1

Plum pudding model discovered by JJ Thompson in 1897.

Question 2

Positive _______ (protons and neutrons) surrounded by negative _________ in ______, discovered by __________.

Answer 2

Positive nucleus (protons and neutrons) surrounded by negative electrons in shells, discovered by Rutherford.

Question 3

How did Rutherford disprove the plum pudding model?

Answer 3

Rutherford disproved plum pudding model by firing alpha particles at gold foil. The
wide scattering pattern suggested the nucleus.

Question 4

Electrons can jump to a ______ energy level (further from the _______) with
absorption of ______________ radiation.

Answer 4

Electrons can jump to a higher energy level (further from the nucleus) with
absorption of electromagnetic radiation.

Question 5

Describe what the plum pudding model was like

Answer 5

A mass of positive charge with negative charged electrons dotted about.

Question 6

what is the radius of an atom

Answer 6

1x10^-10 m

Question 7

what is the central region of the atom called and what is the size of it

Answer 7

the nucleus
1/10000 of the radius of the atom

Question 8

what are the two sub atomic particles found in the nucleus and what are the charges on these
how does this effect the overall charge of the atom

Answer 8

neutrons (neutral) and
protons (positive charge)
leaving the nucleus with an overall positive charge

Question 9

what surrounds the nucleus
what’s the charge

Answer 9

electrons negative charge

Question 10

energy levels which are _______ from the nucleus are at a ______ energy than those which are closer to the nucleus

Answer 10

energy levels which are further from the nucleus are at a higher energy than those which are closer to the nucleus

Question 11

for every element on the periodic table, there are two numbers.
what is the smaller number and what does it tell you

Answer 11

atomic number
number of protons and electrons in the element

Question 12

why do atoms have no overall charge

Answer 12

neutrons have no charge to begin with, and although protons have a positive charge, and electrons have a negative charge then number is always the same meaning the charges cancel each other out

Question 13

for every element on the periodic table, there are two numbers.
what is the larger number and what does it tell you

Answer 13

mass number
number or protons and neutrons

Question 14

what are isotopes

Answer 14

atoms of the same element with a different number of neutrons

Question 15

what happens if an atom looses or gains an electron

Answer 15

it becomes a positive or negative ion

Question 16

what was discovered in 1897
why was this important

Answer 16

electrons
shows that atoms must have an internal structure

Question 17

during the alpha scattering experiment, why was gold foil used

Answer 17

it can be hammered out into just a few atoms thick

Question 18

what particles were fired at the gold foil
what’s the charge

Answer 18

alpha particles
positive

Question 19

what did scientists conclude from the alpha scattering experiment

Answer 19

straight through - atom is mostly empty space
deflected - centre of the atom has a positive charge
bounced back - mass is dfoung in the center

Question 20

why did the alpha particles bounce back off the nucleus

Answer 20

because the alpha particle and nucleus both have a positive charge

Question 21

what did Niels Bohr propose

Answer 21

electrons orbit the nucleus

Question 22

who discovered neutrons and when

Answer 22

James Chadwick
20 years after the nuclear model was first proposed