Chapter 12 Homework

What is the difference between a physical model and a conceptual model?

A physical model is a scale model; a conceptual model is a mental model

How fast does an electron move within an atom?

About 2 million m/s

What causes an atom to emit light?

An atom emits light when it is energized by heat or electricty.

Why do we say atomic spectra are like fingerprints of the elements?

An atom's spectrum has unique characteristic patterns.

Which has more potential energy: an electron close to an atomic nucleus or an electron far from an atomic nucleus?

An electron far from the nucleus has more potential energy.

Distinguish between an atom and an element.

An element is made of only one type of atom

What role does the atomic number play in the periodic table?

Atoms in the periodic table are ordered by increasing atomic number.

Which is heavier: a water molecule, H2O, or a carbon dioxide molecule, CO2?

CO2

What is the atomic symbol for the element cobalt?

Co

Distinguish between atomic number and mass number.

In an atom, the atomic number is the number of protons in the nucleus; the mass number is the sum of the numbers of protons and neutrons.

What does a spectroscope do to the light coming from an atom?

It separates the colors emitted by an atom.

What is an accurate conceptual model able to predict?

Landfall of a hurricane

Distinguish between mass number and atomic mass.

Mass number is the number of protons and neutrons in an atom; atomic mass is the actual mass of the protons, neutrons, and electrons in an atom.

Did Bohr think of his planetary model as an accurate representation of what an atom looks like?

No, he thought it was a conceptual model.

How does the speed of an electron change its fundamental nature?

Slow electrons behave like particles; fast electrons behave like waves.

What is the relationship between the maximum number of electrons each shell can hold and the number of elements in each period of the periodic table?

The number of elements in a period is equal to the maximum number of electrons in its outermost occupied shell.

What happens to the properties of elements across any period of the periodic table?

The properties of elements gradually change across any period of the periodic table.

Does the periodic table explain the shell model, or does the shell model explain the periodic table?

The shell model explains the periodic table.

How do we account for the great variety of substances in the world?

There are many possible combinations of atoms

List several common transition metals

Tungsten, platinum, and iron

When we use a scanning probe microscope, do we see atoms directly or do we only see them indirectly?

We only see them indirectly using an ultra thin needle.

Is there a limit to the number of electrons that can occupy a single shell?

Yes, because of the wave nature of electrons

What is at the center of every atom?

a nucleus

Isotopes are identified by their

atomic mass number

Who first proposed that electrons exhibit the properties of a wave?

de Broglie

Which electrons are most responsible for the properties of an atom?

electrons in the outermost shell

About how fast does an electron travel around the atomic nucleus?

electrons travel at very high speeds; millions of m/s

The elements fluorine, chlorine, and bromine are also known as

halogens

The atoms that make your body

have existed since the start of the universe

Which is the oldest element?

hydrogen

Are most elements metallic, nonmetallic, metalloid, or not yet confirmed?

metallic

An electron, when farther from the nucleus, has

more potential energy

Is it possible to see an atom using visible light?

no

How many types of atoms can you expect to find in a pure sample of any element?

one

A unit of light is the

photon

Which contributes more to an atom's mass: electrons or protons?

protons

How many periods are there in the periodic table? How many groups?

seven periods and 18 groups

What is Planck's quantum hypothesis?

that light energy is quantized

If a baseball were the size of Earth, about how large would its atoms be?

the size of a Ping-Pong ball

Is the head of a politician really made of 99.99999999% empty space?

yes