CHAPTER 14 - REVIEW

There are four forces in nature. Name the four forces and rank them from strongest to weakest.

1. strong nuclear force 2. electromagnetic force 3. weak force; 4. gravity

Rules for energy levels

1.the energy of an electron must match one of the energy levels of the atom 2. each energy level has a characteristic number of electrons it can hold 3.as electrons are added to an atom, they settle to the lowest unfilled energy level

How many electrons can fit in the fourth energy level?

18

The first strong evidence that something smaller than an atom existed was found in

1897 by an English physicist J.J. Thomson. He discovered that electricity passing through a gas caused the gas to give off particles that were too small to be atoms. The new particles and negative electric charge. This are known as electrons.

ELECTRON

A particle with Kan electric charge (-e) found inside of atoms but outside the nucleus.

spectroscope

An instrument that separates light into a spectrum.

isotopes

Atoms of the same element that have different numbers of neutrons

Is electric charge a property of just electricity or is charge a property of all atoms?

Charge is a property of all atoms.

One of the two forces that hold atoms together comes from

Electric charge

Neil Bohr's model

Electrons orbit the nucleus he proposed the concept of energy levels to explain the spectrum of hydrogen. Explaining the spectrum - When an electron moves from a higher energy level to a lower one, the atom gives up the energy difference between the two levels.

quantum mechanics

Energy levels are predicted by quantum mechanics, the branch of physics that deals with the microscopic world of atoms.

Which of the diagrams in Figure 14.16 corresponds to the element lithium?

Lithium's spectrum is represented by the middle diagram.

Two of the energy levels can hold eight electrons each. Which energy levels are they?

The 2nd and 3rd energy levels.

There are three particles inside an atom. One of them has zero electric charge. Which one is it?

The neutron has zero electric charge.

How the energy levels fill

The number of electrons in an atom depends on the atomic number because the number of electrons equals the number of protons.

Nucleus

The tiny core at the center of an atom containing most of the atom's mass and all of its positive charge. EVERY ATOM HAS A TINY NUCLEUS, which contains more than 99 percent of the atom's mass.

spectral line

a bright colored line in a spectroscope

radioactive

a nucleus is radioactive if it spontaneously breaks up, emitting particles or energy in the process.

stable

a nucleus is stable if it stays together.

proton

a particle found in the nucleus with a positive charge exactly equal and opposite to the electron.

neutron

a particle found in the nucleus with mass similar to the proton but with zero electric charge.

Electric charge is

a property of matter and can be either positive or negative.

The electron cloud

a region around the nucleus of an atom where electrons are likely to be found

When an electron moves from a lower energy level to a higher energy level, the atom: a. absorbs light b. gives off light c. becomes a new isotope

a. absorbs light

On average, electrons in the fourth energy level are: a. farther away from the nucleus than electrons in the second energy level b. closer to the nucleus than electrons in the second energy level c. about the same distance from the nucleus as electrons in the second energy level

a. farther away from the nucleus than electrons in the second energy level

The atomic number is: a. The number of protons in the nucleus b. the number of neutrons in the nucleus c. the number of neutrons plus protons

a. the number of protons in the nucleus

Two negative charges will

also repel each other.

Electron define the volume of an

atom

Elements have unique

atomic numbers

A positive and a negative charge will

attract each other.

The element beryllium has four electrons. Which diagram in Figure 14.17 shows how beryllium's electrons are arranged in the first four energy levels?

b.

Which of the following statements regarding electric charge is TRUE? a. A positive charge repels a negative charge and attracts other positive charges. b. A positive charge attracts a negative charge and repels other positive charges.

b. A positive charge attracts a negative charge and repels other positive charges.

Radioactive means: a. an atom gives off radio waves b. the nucleus of an atom is unstable and will eventually change c. the electrons in an atom have too much energy

b. the nucleus of an atom is unstable and will eventually change

All atoms of the same element have ( choose one): a. the same number of neutrons b. the same number of protons c. the same mass

b. the same number of protons

The diagram in Figure 14.10 shows three isotopes of the element carbon. Which one is radioactive?

c

Which of the drawings in Figure 14.9 is the most accurate model of the interior of an atom?

c

The pattern of colors given off by a particular atom is called: a. an orbital b. an energy level c. a spectrum

c. a spectrum

Which two elements have electrons only in the first energy level ? a. hydrogen and lithium b. helium and neon c. hydrogen and helium d. carbon and oxygen

c. hydrogen and helium

complete atoms are

electrically neutral Because protons and electrons attract each other with very large forces the number of protons and electrons in a complete atom is always equal.

The overall size of an atom is the size of its

electron cloud

The first particles discovered that are smaller than atoms

electrons

The letter e represent the

elementary charge Electric charge only appears in multiples of the elementary charge, e. +e, -e, +2e, -2e, +3e, -3e Impossible for ordinary matter to have charges that are fractions of e. +0.5e, +2.5e, -1.5e

How many neutrons are present in an aluminum atom that has an atomic number of 13 and a mass number of 27?

equation: protons + neutrons = mass numbers plug in and solve: 13 + x = 27 x = 27 - 13 x = 14 the aluminum atom has 14 neutrons

The force of ______________ inside the atom is much weaker than even the weak force.

gravity

gamma decay

how the nucleus gets rid of excess energy.

uncertainty principle

it is impossible to know variables precisely in the quantum world. ON a much smaller scale, an electron has no definite shape or position. German physicist Werner Heisenberg (1901-1976)

The nucleus contains most of the

mass

protons + neutrons =

mass number

The energy levels are at different distances from the

nucleus The positive nucleus attracts negative electrons like gravity attracts a ball down a hill.

energy level

one of the discrete allowed energies for electrons in an atom.

Light is a form of pure energy that comes in tiny bundles called

photons A photon is the smallest possible quantity of light energy. The amount of energy in a photon determines the color of the light.

There are two different kinds of electric charge -

positive and negative

electromagnetic forces

positive or negative forces- similar charges repel each other opposite charges attract each other

ions

positively and negatively charged atoms ions are atoms that have a different number of protons than electrons and so have a net electric charge.

The nucleus of an atom contains

protons and neutrons

Two positive charges will

repel each other.

Each individual color in a spectrum is called a

spectral line

The strongest known force in the universe

strong nuclear force

spectrum

the characteristic colors of light given off or absorbed by an element. The spectrum is a pattern of colors.

How electrons fill in the energy levels

the first energy level - up to 2 electrons the second & third level - up to 8 electrons the fourth & fifth level - up to 18 electrons Electrons occupy energy levels around the nucleus. The farther away an electron is from the nucleus, the higher the energy it possesses.

atomic number

the number of protons in the nucleus of an atom. The atomic number determines what element the atom represents.

The atomic number is

the number of protons in the nucleus of every atom of that element.

quantum theory

the theory that describes matter and energy at very small (atomic) sizes

mass number

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

There is another nuclear force called

the weak force. The weak force is weaker than both the electric force and the strong nuclear force.

beta decay

when a neutron in the nucleus splits into a proton and an electron.

alpha decay

when the nucleus ejects two protons and two neutrons.