topic 3.1
who was the first person to propose the idea that matter was not infinitely divisible?
a. John Dalton
b. Thompson
c. Aristotle
d. Democritus
d. Democritus
What are the parts of the atom?
protons, neutrons, electrons
what particle of the atom determines the identity of the atom?
the proton
some substances emit radiation spontaneously. We say the substance is .....
radioactive
Who is responsible for the postulates of the modern atomic theory?
a. Democritus
b. JJ Thompson
c. John Dalton
d. Ernest Rutherford
John Dalton
Who invented the cathode ray tube?
a. JJ Thomson
b. E. Rutherford
c. William Crookes
d. John Dalton
William Crookes
what is the weighted average mass of the isotopes of an element?
atomic mass
a reaction that involves a change in an atom's nucleus is called
nuclear reaction
True or false: Atoms of a given element are identical in size , mass, and chemical properties
false, isotopes have different mass number, different neutrons
What is Thomson's atomic model called?
plum pudding model
true or false: in the hyphen notation the atomic number is written after the hyphen symbol.
false: mass number
the particles emitted in radioactive decay are
alpha particles, beta particles.
True or false: Daltons atomic theory agrees on the law of conservation of mass
true
Who discovered the atomic nucleus using alpha particles?
E. Rutherford
Calculate the average atomic mass of element x that has 95% abundance with a mass of 45 amu and the rest is 49 amu.
the final answer should resemble 45 amu. This is the most abundant isotope
write the nuclear symbol of xenon-132
132
Xe
54
What is the name of the particle that is 1/2000 as large as the proton?
electron
nitrogen has two naturally occurring isotopes: nitrogen -14 and nitrogen-15. Its atomic mass is 14.007. Which isotope is more abundant? Explain your answer
nitrogen 14 because is the most abundant
which of the following is stopped by lead walls?
gamma rays