Midterm Review

Valence Electrons

Valence Electrons

Electrons in the outermost energy level of an atom that are typically involved in chemical reactions by being gained, lost, or shared in the formation of chemical bonds.

Intramolecular force

forces that hold atoms and ions together in molecules and compounds

Ionic Bond

Formed when one or more electrons are transferred from one atom to another

Cation

A positively charged ion, usually a metal atom

Anion

A negatively charged ion, usually a nonmetal

Covalent Bonds

Bonds created by sharing electrons with other atoms. Usually nonmetals.

Metallic Bond

a bond formed by the valence electrons moving freely through the metallic substance, often described as a 'sea of mobile electrons'.

Intermolecular force

a weak force of attraction between molecules , includes hydrogen bonds and van der Waals forces

Hydrogen bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom, the strongest intermolecular force

Dipole

a molecule that has two poles, or regions, with opposite charges

dipole-dipole forces

attractions between oppositely charged regions of polar molecules

van der Waals forces

a slight attraction that develops between the temporary dipoles in nearby molecules, the weakest intermolecular force

Polyatomic ion

A charged group of covalently bonded atoms (see table E)

Chemical Bond

the attractive force that holds atoms or ions together

According to the law of conservation of mass, the mass of the compound is _______ the sum of the masses of the individual elements

equal to

According to Dalton's atomic theory, atoms

of each element are identical in size, mass, and other properties

True or false: atoms of the same element may have different masses?

True

Experiments with cathode rays led to the discovery of the

electron

Whose series of experiments identified the nucleus of the atom?

Rutherford

Because most particles fired at metal foil passed straight through, Rutherford concluded that

atoms were mostly empty space

A positively charged particle with mass 1 amu is a

proton

A nuclear particle that has about the same mass as a proton but with no electrical charge is called a

neutron

True or false: The nucleus of an atom is positively charged

true

True or false: The nucleus of an atom contains nearly all of the atom's mass

true

True or false: The nucleus of an atom is very dense

true

True or false: The nucleus of an atom contains nearly all of the atom's volume

false

Which part of an atom has a mass approximately equal to 1/2000 of the mass of a common hydrogen atom?

electron

Protons within the nucleus are attracted to each other by

the nuclear force, also called the strong force

An atom is electrically neutral because

the numbers of protons and electrons are equal

Most of the volume of an atom is occupied by the

electrons and lots of empty space

The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the

atom

The radius of an atom extends to the outer edge of the

region occupied by the electrons

Isotopes are atoms of the same element that have different

masses

The atomic number of oxygen, 8, indicates that there are 8

protons in the nucleus of an oxygen atom

As the atomic number increases, the number of electrons in a neutral atom

increases

All atoms of the same element have the same

atomic number

The relative atomic mass of an atom can be found by comparing the mass of the atom to the mass of

one atom of carbon-12

The average atomic mass of an element is the average of the atomic masses of its

naturally occurring isotopes

An aluminum isotope consists of 13 protons, 13 electrons, and 14 neutrons. Its mass number is

27

Neon-22 contains 12 neutrons. It also contains

10 protons and 10 electrons

The energy of a photon is related to its

frequency

A bright line spectrum is produced when an electron moves from one energy level

to a lower energy level

When the pink-colored light of glowing hydrogen gas passes through a prism, it is possible to see

four lines of different colors (bright line spectrum)

The Bohr model of the atom was an attempt to explain hydrogen's

line-emission spectrum

For an electron in an atom to change from the ground state to an excited state,

energy must be absorbed

If electrons in an atom have the lowest possible energies, the atom is in the

ground state

According to the Bohr model of the atom, the single electron of a hydrogen atom circles the nucleus

in specific, allowed orbits

A three dimensional region around a nucleus where an electron may be found is called a(n)

orbital

True or false: According to the wave mechanical model of an atom, or modern model, an electron's position in an orbital cannot be known precisely.

True

True or false: According to the wave mechanical model of an atom, or modern model, in an orbital electrons travel around the nucleus in paths of specific radii

False

How many electron shells does an element in Period 2 of the periodic table have?

2

True or false: Two electrons can occupy the first principal energy level of an atom

True

True or false: Eight electrons can occupy the second principal energy level of an atom.

True

How many electrons are needed to completely fill the third energy level?

18

If the third main energy level contains 15 electrons, how many more could it possibly hold?

3

The principal energy level that can hold only two electrons is the

first

An element with 8 electrons in its highest main energy level is a

noble gas

The idea of arranging the elements in the periodic table according to their chemical and physical properties is attributed to

Mendeleev

Mendeleev left spaces in his periodic table and predicted the existence of three elements and their

properties

Mendeleev noticed that properties of elements usually repeated at regular intervals when the elements were arranged in order of increasing

atomic mass

Mendeleev predicted that the spaces in his periodic table represented

undiscovered elements

Moseley's work led to the realization that elements with similar properties occured at regular intervals when the elements were arranged in order of increasing

atomic number

The discovery of what elements added a new column to Mendeleev's periodic table?

noble gases

What are the radioactive elements with atomic numbers from 90 to 103 called?

actinides

What are the elements with atomic numbers from 58 to 71 called?

lanthanides

Argon, krypton, and xenon are

noble gases

The periodic law states that the physical and chemical properties of elements are periodic functions of their atomic

numbers

The principle that states that the physical and chemical properties of the elements are period functions of their atomic numbers is

the periodic law

Elements in a group or column in the periodic table can be expected to have similar

properties

To which group do fluorine and chlorine belong? (name and group #)

Group 17; halogens

A horizontal row of blocks in the periodic table is called a

period

Potassium and bromine belong to what period?

4

Elements to the right side of the periodic table have properties most associated with

nonmetals

Elements to the left side of the periodic table are the

metals

Hydrogen is placed separately from other elements in the periodic table because it

has many unique properties

Bromine, atomic number 35, belongs to Group 17. How many electrons does bromine have in its outermost energy level?

7

The elements in Group 1 are also know as the

alkali metals

The most reactive group of the nonmetals is the

halogens

The group of soft, silvery, reactive metals, all of which have one electron in their valence shell, are known as the

alkali metals

The most characteristic property of the noble gases is that they

are largely unreactive

Compared to the alkali metals, the alkaline earth metals

are less reactive

The energy required to remove an electron from an atom is the atom's

ionization energy

A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound is called

electronegativity

What is removed when the ionization energy is supplied to an atom of an element?

an electron

A positive ion is known as a(n)

cation

A negative ion is known as a(n)

anion

Within a group of elements, as the atomic number increases, the atomic radius

increases

Across a period in the periodic table, atomic radii

gradually decrease

Which is the best reason that the atomic radius generally increases with atomic number in each group of elements?

The number of occupied energy levels increases

The electrons available to be lost, gained, or shared when atoms form compounds are called

valence electrons

Valence electrons for representative elements (Group 1&2, 13-18) are found in their

highest occupied energy level

The number of valence electrons in Group 17 elements is

7

The element with electron configuration 2-8-4 is

Silicon

The electron configuration for the carbon atom (C) is 2-4. The atomic number of carbon is

6

The electron configuration for aluminum (atomic number 13) is

2-8-3

Write the electron configuration for nitrogen, atomic number 7

2-5

What is a possible electron configuration for Nitrogen in the excited state

2-4-1

What is a possible electron configuration for Chlorine in the excited state

2-7-8

What period is aluminum in?

3

In what period is cesium?

6