PHS ch 12 homework

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

7 periods and 18 groups

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 an it is energized by heat or electricity

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

An atoms spectrum has unique characteristic patterns

Distinguish between an atom and an element

An element is made of only one type of atom

Distinguish between atomic number and mass number

Atomic number is the number of protons in the nucleus. Mass number is the total number of protons and neutrons in the nucleus.

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, H20 or a carbon dioxide molecule, CO2?

CO2

What is the atomic symbol for the element cobalt?

Co

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

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

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

Metallic

Is it possible to see an atom using visible light

No

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

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

Protons contribute more to an atom's mass while electrons contribute more to its size.

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

Slow electrons behave like particles; fast electrons behave like waves

What is plancks quantum hypothesis?

That light energy is quanitzed

What relationship between the maximum number of electrons each shell can hold and the 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 the 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.

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

The size of a large ping pong ball

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 only indirectly?

We only see them indirectly using an ultra thin needle

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

Yes

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

Yes bc of the wave nature of electrons

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

an electron far from an atomic nucleus has more potential energy

Isotopes are identified by their

atomic mass number

An electron, when farther from the nucleus, has

more potential energy

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