Chapter 4 Study Guide

Is the density of a nucleus high or low?

It is very dense because all the particles with significant mass (protons and neutrons) are located there and it is a very small volume compared to the entire atom's volume. All of its mass is concentrated in a very small volume.

If you had a bunch of isotope symbols, how would you determine which are isotopes of the same element?

The symbols with the same atomic number (the lower, left number) would be the same element.

proton

a positively charged subatomic particle

neutron

a subatomic particle with no charge

How many protons are in a neutral atom of aluminum? You need a periodic table to answer this question.

aluminum's atomic number is 13 so it will have 13 protons

What discovery did J. J. Thompson make with the cathode ray tube

atoms contain negatively charged particles

isotope

atoms with the same number of protons but different number of neutrons in the nucleus of the atom

What does the number 42 mean in the name calcium-42

calcium-42 is the name of a specific isotope of calcium and the 42 is its mass number

What is the atomic number for an atom containing 18 neutrons and its mass number is 33?

15 The mass number is the total of protons and neutrons so if you subtract the neutrons from the mass number you get the protons only

electron

a negatively charged subatomic particle

Which two parts of Dalton's Atomic Theory have been revised?

1. Atoms are not indivisible (atoms can be split) 2. All atoms of an element are NOT identical (they can have different number of neutrons)

How many neutrons are in oxygen-18? You need a periodic table to answer this question.

10 18 is the mass number which is protons and neutrons together. The atomic number of oxygen (8) indicates how many protons there are. 18 minus 8 gives 10 neutrons.

How many electrons are in an atom of silicon?

14 The atomic number is 14 so it would have 14 electrons to balance the 14 protons inside the nucleus.

What is the mass number of an atom of sulfur that has 18 neutrons in its nucleus?

34 The mass number is the total of protons and neutrons. The atomic number of sulfur is 16 so it has 16 protons. 16 plus 18 equals 34.

How many neutrons are in an atom of ⁷⁵Br? You need a periodic table to answer this question.

40 To do this you need to look at the periodic table to find the atomic number of Br (it is 35). Then 75 minus 35 equals 40 neutrons.

How many neutrons are in an atom of ¹⁰⁴₅₀Sn?

54 The mass number (p⁺ and n⁰) minus atomic number (p⁺ only) gives the number of neutrons. 104 minus 50 equals 54 neutrons.

Calculate the atomic mass of element Z with the following percent abundances: the isotope with mass number 60 is 30% abundant and the isotope with mass number 62 is 70% abundant

61.4 Before doing the calculation it should be obvious that the answer must be between 60 and 62. And since the greatest percent is 62 the answer will be closer to 62 than to 60. The solution is: (60 x .30) + (62 x .70) = atomic mass

atomic mass

the weighted average of the masses of the isotopes of an element

Using the periodic table determine the number of neutrons in ³²P

17 The periodic table show that P has atomic number 15. That means it has 15 protons. The 32 in the partial isotope symbol is the mass number which is the protons AND neutrons added together. The mass number (p⁺ and n⁰) minus ther atomic number (p⁺ only) gives the number of neutrons. 32 minus 15 gives the number of neutrons only which is 17.

How many protons and electrons are in an atom with atomic number of 17?

17 protons and 17 electrons. Atomic number is defined to be the number of protons in the nucleus. And to be neutral it must also contain the same number of electrons.

How many protons are in an atom of uranium-235?

92 The atomic number of uranium is 92 so it will have 92 protons

How many protons, neutrons and electrons are in ²²₁₀Ne?

There are 10 protons because the atomic number is 10 There are also 10 electrons because to be neutral an atom must have the same number of protons and electrons There are 12 neutrons. The mass number (22) is p⁺ and n⁰ combined so subtracting the atomic number (10) gives the number of neutrons.

How many protons, neutrons and electrons are in an atom with atomic number 30 and mass number 63?

There are 3o p⁺, 30 e⁻ and 33 n°

How are the atoms of one element always different from those of another element?

There is only one thing that is always different from one element to the next. They will always have the same number of protons

Atoms are electrically neutral. Why is that?

They have the same number of positively charged protons and negatively charged electrons

What do all atoms of the same element have the same number of?

They will always have the same number of protons.

How many electrons are in a neutral atom of zinc? You need a periodic table to answer this question.

Zinc's atomic number is 30 so it will have 30 electrons in order to balance the 30 protons in the nucleus

What is the total number of subatomic particles in ⁸⁵₄₀Zr

Zr will have 40 protons, 40 electrons and 45 neutrons (mass # minus atomic #). So it has a totla of 125 subatomic particles.

What do the isotopes of a given element have that's always different?

different number of neutron and as a result a different mass number also

nucleus

the central part of an atom containing protons and neutrons

atomic number

the number protons in the nucleus of an element

atom

the smallest particle of an element that retains the properties of that element

mass number

the total number of protons and neutrons in the nucleus of an element

How do the isotopes of carbon-12 and carbon-13 differ?

Carbon 13 has one more neutron than carbon-12 and its mass is greater by 1

What two factors does the atomic mass of an element depend on?

It depends on the actual masses of the isotopes and the relative abundance of each. Think of it this way, doesn't the average weight of a first grade class differ than the average weight of a high school class because the mass of the kids are very different between 1st grade and high school? And doesn't the average weight of a high school class depend on the relative abundance of males and females in the class? A class with mostly males will weigh more than a class with mostly females.

What did Millikan's Oil Drop experiment determine?

It determined the quantity of charge carrtied by an electron

What observation led Rutherford to believe that atoms are mostly empty space?

Most of the alpha particles passed through the gold foil without being deflected

What observation led Rutherford to believe that almost all of the mass is contained in the nucleus?

Some of the alpha particles were bounced back

atomic mass unit

one twelfth the mass of a carbon atom containing 6 protons, 6 neutrons and 6 electrons

If a nucleus contains both protons and neutrons, what is its overall charge?

positive because the protons are positive and the neutrons have no charge