Download Chapter 4 The structure of the Atom

Chapter 4 The structure of the Atom
Section 4.1 Early ideas about matter
1. What did Greek philosophers think about the composition of matter?
Matter was composed of earth, water, air and fire.
2. Which philosopher thought that atoms could not be created, destroyed, or divided,
and also named the atom “atomos”?
Democritus
3. Who did not believe that empty space could exist, and also helped in rejecting
Democritus theory?
Aristotle
4. Who developed the modern atomic theory?
John Dalton
5. Write the main postulates of Dalton’s atomic theory?
 Matter is composed of small particles called atoms
 Atoms are indivisible and indestructible
 Atoms of a given element are identical in size, mass, and chemical
properties
 Atoms from different elements are different
 Atoms combine in simple whole-number ratios
Section 4.2 defining the atom
6. What is an atom?
The smallest particle of an element that retains its properties
7. What is the purpose of the scanning tunneling microscope?
Allows a person to see individual atoms
8. What is the use of a cathode-ray tube?
To study the relationship between mass and electrical charge
9. How did the cathode ray originate?
A cathode ray originates as the charged particles pass from the cathode to the
anode in a cathode tube
10. Who received Nobel recognition for identifying the electron?
J.J. Thomson
11. Who determined that the electron possessed a negative charge and also calculated
the mass of the electron?
Robert Millikan
12. What was the name of the atomic model proposed by J.J Thompson? And how
did it look?
The plum pudding model, this model considered the atom to have positively and
negatively charged particles within.
11. Explain Rutherford’s experiment?
The experiment tried to determine the properties of the nucleus including relative
size and density
12. How was Rutherford’s atomic model?
Rutherford considered the atom to be made of mostly empty space, and the
positive charges of the atom are concentrated in the center of the atom which he
named the nucleus.
13. Who discovered the neutral particle of the atom?
James Chadwick
14. Which are the three subatomic particles of the atom?
Electron, proton, and neutron
Section 4.3 How atoms differ
13. Who stated that the proton is the subatomic particle that identifies an atom from a
particular element?
Henry Moseley
14. The number or protons in the nucleus is also referred as the Atomic number
15. The atomic number =_____________ and =_________________
16. What is an isotope?
Atoms with the same number of protons but different number of neutrons
17. How do you identify an isotope?
By the mass number
18. What is the mass number?
The sum of the atomic number and the neutrons in the nucleus
19. Write some characteristics of isotopes
Same chemical behavior
Their abundance is constant
Most elements are found as mixtures of isotopes
20. What is the atomic mass unit?
Is a method of measuring the mass of an atom relative to the mass of the
carbon-12 atom. Since C-12 has exactly six protons and six neutrons. Each of
these particles was given an arbitrary value of one.
21. What is the atomic mass?
It is the weighted average mass of the isotopes of an element.
Section 4.4 Unstable nuclei and radioactive decay
22. What is radioactive decay?
The emission or radiation through the process of nuclear decay
23. Which particles are given off during nuclear decay?
Alpha, beta, gamma.
24. What is the primary factor in determining if the atom’s stability?
The ratio of neutrons and protons