Chapter 4

Define atom using your own words.

Summarize Dalton’s atomic theory.

Explain how Dalton’s theory of the atom and the conservation of mass are related.

Apply Six atoms of Element A combine with 15 atoms of Element B to produce six compound particles. How many atoms of Elements A and B does each particle contain? Are all of the atoms used to form compounds?

Design a concept map that compares and contrasts the atomic ideas proposed by Democritus and John Dalton.

Describe the structure of a typical atom. Identify where each subatomic particle is located.

Evaluate the experiments that led to the conclusion that electrons are negatively charged particles found in all matter.

Compare the relative charge and mass of each of the subatomic particles

An atom of an element contains 66 electrons. Which element is it?

An atom of an element contains 14 protons. Which element is it?

Challenge An atom has a mass number of 55. Its number of neutrons is the sum of its atomic number and five. How many protons, neutrons, and electrons does this atom have? What is the identity of this atom?

Boron (B) has two naturally occurring isotopes: boron-10 (abundance \(=19.8 \%\) , mass \(=10.013\) amu) and boron-11 (abundance \(=80.2 \%,\) mass \(=11.009\) amu). Calculate the atomic mass of boron.

Challenge Nitrogen has two naturally occurring isotopes, N-14 and N-15. Its atomic mass is 14.007. Which isotope is more abundant? Explain your answer.

Explain how the type of an atom is defined.

Recall Which subatomic particle identifies an atom as that of a particular element?

Explain how the existence of isotopes is related to the fact that atomic masses are not whole numbers.

Calculate Copper has two isotopes: \(C u-63\) (abundance \(=69.2 \%\) mass \(=62.930\) amu) and \(C u-65\) (abundance \(=30.8 \%,\) mass \(=64.928\) amu). Calculate the atomic mass of copper.

Calculate Three magnesium isotopes have atomic masses and relative abundances of 23.985 amu \((79.99 \%), 24.986\) amu \((10.00 \%),\) and 25.982\((11.01 \%) .\) Calculate the atomic mass of magnesium.

State what quantities are conserved when balancing a nuclear reaction

State what quantities are conserved when balancing a nuclear reaction

Classify each of the following as a chemical reaction, a nuclear reaction, or neither. a. Thorium emits a beta particle. b. Two atoms share electrons to form a bond. c. A sample of pure sulfur emits heat energy as it slowly cools. d. A piece of iron rusts.

Calculate How much heavier is an alpha particle than an electron?

Who originally proposed the concept that matter is composed of tiny, indivisible particles?

Whose work is credited with being the beginning of modern atomic theory?

Ideas and Scientific Methods Was Democritus’s proposal of the existence of atoms based on scientific methods or ideas? Explain.

Explain why Democritus was unable to experimentally verify his ideas.

What was Aristotle’s objection to the atomic theory?

State the main points of Dalton’s atomic theory using your own words. Which parts of Dalton’s theory were later found to be erronous? Explain why.

Define matter and give two everyday examples.

What particles are found in the nucleus of an atom? What is the charge of the nucleus?

How was the overall charge distributed in the plum pudding model?

How did the charge distribution in the plum pudding model affect alpha particles passing through an atom?

Arrange the following subatomic particles in order of increasing mass: neutron, electron, and proton.

Explain why atoms are electrically neutral.

What is the charge of the nucleus of element 89?

Which particles account for most of an atom’s mass?

If you had a balance that could determine the mass of a proton, how many electrons would you need to weigh on the same balance to measure the same mass as that of a single proton?

Cathode-Ray Tubes Which subatomic particle was discovered by researchers working with cathode-ray tubes?

Briefly explain how Rutherford discovered the nucleus.

Particle Deflection What caused the deflection of the alpha particles in Rutherford’s gold foil experiment?

What is the approximate size of an atom?

Vizualizing Atoms What technique can be used to visualize individual atoms?

What are the strengths and weaknesses of Rutherford’s nuclear model of the atom?

How do isotopes of a given element differ? How are they similar?

How is an atom’s atomic number related to its number of protons? To its number of electrons?

How is the mass number related to the number of protons and neutrons an atom has?

How can you determine the number of neutrons in an atom if its mass number and its atomic number are known.

What do the superscript and subscript in the notation \(_{19}^{40} \mathrm{K}\) represent?

Standard Units Define the atomic mass unit. What were the benefits of developing the atomic mass unit as a standard unit of mass?

Isotopes Are the following elements isotopes of each other? Explain. $$\begin{array}{l}{24} \\ {12}\end{array} \mathrm{Mg}, \begin{array}{c}{25} \\\ {12}\end{array} \mathrm{Mg}, \begin{array}{l}{26} \\ {12}\end{array} \mathrm{Mg}$$