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Flashcards in Radioactivity and stuff Deck (21)
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1
Q

Meaning of “atomos”

A

indivisible

2
Q

The idea of atoms was conceived by ___ and ___.

A

Leucippus and Democritus.

3
Q

He thought that the world was composed of air, earth, fire, and water.

A

Empedocles

4
Q

Created the atomic theory.

A

John Dalton

5
Q

negatively charged particles

A

electrons

6
Q

Measured the charge of electrons with his oil drop experiment

A

Robert Millikan

7
Q

He discovered that highly energetic rays could penetrate matter.

A

Wilhelm Roentgen

8
Q

He associated X_rays with fluorescent materials.

A

Henri Becquerel.

9
Q

Any material that spontaneously emits radiation is said to be ___.

A

radioactive

10
Q

Particles with a positive charge of +2.

A

Alpha rays

11
Q

Negatively charged electrons which are attracted to positively charged plates.

A

Beta rays

12
Q

Electromagnetic radiation of extremely high penetrating power.

A

Gamma rays

13
Q

Ernest Rutherford’s 21-year old student.

A

Ernest Marsden

14
Q

Rutherford’s assistant who used alpha particles to probe the atom.

A

Hans Geiger

15
Q

Positively charged parts of the atom

A

Protons

16
Q

A small region at the center of the atom.

A

Nucleus

17
Q

One of Rutherford’s students

showed that each uncharged particle emitted by radioactive atoms has a mass approx. equal to a proton.

A

James Chadwick

18
Q

neutral charged particles

A

Neutrons

19
Q

Atoms of the same element that have different number of neutrons.

A

Isotopes

20
Q

Number of protons is equal to___.

A

Atomic number

21
Q

p+n

A

Atomic mass