Chem Midterm

photoelectric effect

The emission of electrons from a metal when light shines on the metal

electron affinity - releases energy

The energy change that occurs when an electron is acquired by a neutral atom is called the atom's electron affinity. Values usually negative because energy is usually released in this process, as opposed to ionization energy, which requires energy. A more negative electron affinity corresponds to a greater attraction for an electron. Electron affinity becomes less negative down a group.

ionization energy (kJ/mol). how does it change across the periodic table? Does it (increase or decrease) from left to right across a period Does it (increase or decrease) down a group

The energy required to remove one electron from a neutral atom of an element Ionization energy increase from left to right across a period and decrease down a group Ionization energy increases with each successive electron removed from an atom Atoms that want to lose electrons to achieve greater stability have LOW Ionization Energies. Atoms that want to gain electrons to achieve greater stability have HIGH Ionization Energies.

ground state vs excited state of an atom what happens when an excited atom returns to ground-state?

The lowest energy state of an atom is its ground state.(only one ground state for an atom) A state in which an atom has a higher potential energy than it has in its ground state is an excited state. (many possible excited states for an atom) When an excited atom returns to its ground state or a lower-energy excited state, it gives off the energy it gained in the form of electromagnetic radiation. Ex. The production of colored light in neon signs

Explain why most metals are malleable and ductile but ionic crystals are not.

The malleability and ductility of metals are possible because metallic bonding is the same in all directions throughout the solid. Crystals cannot be shifting the layers of an ionic crystal causes the bonds to break and the crystal to shatter.​

The periodic law states that _____

The physical and chemical properties of the elements are periodic functions of their atomic numbers.

5.1

The properties of the chemical elements are a periodic function of their atomic numbers.​

energy shell Do electrons (further or closer) to the nucleus have greater energy? How are energy shells designated? Subshells

a collection of orbitals with roughly similar sizes Electrons that are farther from the nucleus have greater energy than those that are closer. Therefore, electrons in the orbitals of larger energy shells have greater energy than those in the orbitals of smaller energy shells Each energy shell is designated by a whole number, so we have 1st (smallest), 2nd, 3rd, etc. Subshell - orbitals that have the same shape in a given energy shell

What is electromagnetic radiation? Name 5 types of electromagnetic radiation Together, all the forms of electromagnetic radiation form the ___________________

a form of energy that exhibits wavelike behavior as it travels through space. 5 types of e-mag radiation: - Visible light - x-ray - ultraviolet and infrared ligh, -microwaves - radio waves electromagnetic spectrum Electromagnetic radiation travels in the form of waves covering a wide range of wavelengths and frequencies.This range is known as the electromagnetic spectrum. Only a small portion of the spectrum, from 400 nm to 700 nm, is visible to the human eye.

Lanthanide (f-block)

a member of the rare-earth series of elements, whose atomic numbers range from 58 (cerium) to 71 (lutetium)

chemical bond

a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together.

Lewis Structures

a way of representing molecular structures based on valence electrons Tells structure of a molecule Dots are unshared electrons Dashes are shared pairs of electrons (bond) Two dashes means two pairs of electrons are shared (4 e- total) Goal is to have complete octet around each atom (with a few exceptions) H=2 Be=4 B=6 P=10 S=12

Alkaline Earth Metals (Group 2)

beryllium, magnesium, calcium, strontium, barium, and radium Atoms of alkaline-earth metals contain a pair of electrons in their outer- most s sublevel. Consequently, the group configuration for Group 2 is ns2. The Group 2 metals are harder, denser, and stronger than the alkali metals. They also have higher melting points. Although they are less reactive than the alkali metals, the alkaline-earth metals are also too reactive to be found in nature as free elements.​

radioactivity

changes that occur within an atom's nucleus

Aufbau principle

electrons occupy the lowest energy orbital first

Halogens (Group 17)

fluorine, chlorine, bromine, iodine, and astatine The halogens are the most reactive nonmetals. They react vigorously with most metals to form salts. The reactivity of the halogens is based on the presence of seven electrons in their outer energy levels—one electron short of the stable noble-gas configuration.

Electron Density

gives the probability that an electron will be found in a particular region of an atom

Electrons that are not in the highest occupied energy level are called ______

inner-shell electrons

Bonding - types of bonds (3)

ionic - electron transferred covalent - electron shared polar-covalent - electron shared unequally

An is composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal.

ionic compound

Heisenberg uncertainty principle

it is impossible to know exactly both the velocity and the position of a particle at the same time electrons are located in orbitals, not orbits

line-emission spectrum vs continuous spectrum What color of the visible spectrum has the longest wavelength?

line-emission: a series of specific wavelengths of electromagnetic radiation emitted by electrons as they move from higher to lower energy states Every element has a different emission spectrum, can use emission spectrum to help identify an element. continuous spectrum: an unbroken sequence of frequencies or wave-lengths of electromagnetic radiation, often emitted by an incandescent source Red

quantum number - electron address, tells you where the electron is located relative to the nucleus of the atom Every electron has 4 quantum numbers: - principal quantum number - angular momentum quantum number - magnetic quantum number - spin quantum number

quantum number - a number that specifies certain properties of electrons principal quantum number (n)- distance from nucleus first shell (n=1) is closest to nucleus angular momentum quantum number (l) - shape of orbital s-subshell=0, p-subshell=2, d-subshell=2, f-subshell=3 magnetic quantum number (ml)- orientation of an orbital around the nucleus s-subshell - 1 orbital: 0 p-subshell - 3 orbitals: -1,0,+1 d-subshell - 5 orbitals: -2,-1,0,+1,+2 spin quantum number (s) describes the electron spin Every orbital has 2 electrons and they must spin in opposite directions (+1/2 and -1/2)

Orbital shape (4 types)

s - 1 circle p - 3 dumbells d -5 oddly shaped f - 7 oddly shaped

Based on the electron configurations of the elements, the periodic table can be divided into four blocks: the s-block, the p-block, the d-block, and the f- block.

s and p - main group d block - transition elements f block - lanthanides and actinides

electron configuration what are the 3 types of notation?

the arrangement of electrons in an atom orbital notation, electron-configuration notation, and noble-gas notation.

electron configuration

the arrangement of electrons in an atom. tells us the energy levels and orbitals that the electrons inhabit in the atom

bond length

the average distance between the nuclei of two bonded atoms

transition elements/metals (D-block)

the d-block elements are metals with typical metallic properties and are often referred to as transition elements. They are good conductors of electricity and have a high luster. They are typically less reactive than the alkali metals and the alkaline-earth metals. Some are so nonreactive that they do not easily form compounds and exist in nature as free elements. Palladium, platinum, and gold are among the least reactive of all the elements. atoms contain partially filled d sub levels when they are in the ground state

Bohr's model What was proven incorrect about it?

the electrons surrounding the nucleus orbit at fixed distances Incorrect assumption that electrons orbit the nucleus like planets orbit the sun The biggest jumps are called Lyman the middle are Balmer and the smallest are Paschen

BOND ENERGY

the energy required to break a chemical bond and form neutral isolated atoms

Frequency (ν) is _____ The unit for frequency is ____ One wave/second is called a _____

the number of waves that pass a given point in a specific time, usually one second. Frequency is expressed in waves/second. One wave/second is called a hertz (Hz),

quantum theory

the study of the structure and behavior of the atom and of subatomic particles from the view that all energy comes in tiny, indivisible bundles • Quantum theory was developed to explain observations such as the photoelectric effect and the line-emission spectrum of hydrogen. • Quantum theory states that electrons can exist only at specific atomic energy levels.

covalent bond (nonpolar)

A chemical bond formed when two atoms share electrons - the shared electrons are "owned" equally by the two bonded atoms.​ resulting in a balanced distribution of electrical charge.

form from attractions between positive and negative ions.

Ionic bonds

What was the major shortcoming of Rutherford's model of the atom?

It did not explain how the atom's negatively charged electrons are distributed in the space surrounding its positively charged nucleus. Reminder: Rutherford shot a beam of helium atoms at a sheet of gold foil. The majority of atoms passed through, but a small percentage were deflected by the foil. This experiment led to the theory that there was a highly dense nucleus located at the center of the atom and that had sufficient mass to deflect the helium atoms.

the energy released when one mole of an ionic crystalline compound is formed from gaseous ions

Lattice energy

6.2 ​Covalent Bonding and Molecular Compounds​

Main Ideas: -Covalent bonds form from shared electrons. - Bond lengths and energy vary from molecule to molecule. - Atoms tend to form bonds to follow the octet rule. - Dots placed around an element's symbol can represent valence electrons. -Electron-dot notations can represent compounds. -Some atoms can share multiple pairs of electrons. -Resonance structures show hybrid bonds. -Some compounds are networks of bonded atoms.

6.3 Ionic Bonding and Ionic Compounds

Main Ideas: -Ionic bonds form from attractions between positive and negative ions. - Differences in attraction strength give ionic and molecular compounds different properties. - Multiple atoms can bond covalently to form a single ion.

Most metals are also easy to form into desired shapes. Two important properties related to this characteristic are

Malleability is the ability of a substance to be hammered or beaten into thin sheets. Ductility is the ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire. T

Noble Gases (Group 18)

Stable / Group 18 have a full outer s and p sub-shells of 8 electrons and, therefore, are stable and tend not to form ions last group discovered/added to periodic table

Octet rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

Differences in attraction strength give ionic and molecular compounds different properties.

The force that holds ions together in ionic compounds is a very strong overall attraction between positive and negative charges. In a molecular compound, the covalent bonds of the atoms making up each molecule are also strong. But the forces of attraction between molecules are much weaker than the forces among formula units in ionic bonding. This difference in the strength of attraction between the basic units of molecu- lar and ionic compounds gives rise to different properties in the two types of compounds

What is the relationship between Bond Energy and Bond Length?

The higher the bond energy, the 'stronger' the bond is between the two atoms, and the distance between them (bond length) is smaller.

How do the sizes of cation and anions compare to the size of the neutral atoms from which they are formed?

The ionic radii of cations are always smaller than the atoms they were formed from. (Because they lose an electron, so they have more protons than electrons). The ionic radii of anions are always larger than the atoms they were formed from (Because they gain an electron, so they have more electrons than protons.)

main-group elements (representative elements/p-block and s-block)

The p-block and s-block elements Groups 1-2; 13-18.

Electron Dot Notation

an electron-configuration notation in which only the valence electrons of an atom of a particular element are shown, indicated by dots placed around the element's symbol

Actinide (f-block)

any of the series of heavy radioactive elements that extends from thorium (atomic number 90) through lawrencium (atomic number 103) on the periodic table

Wavelength (λ) is _______ The unit for wavelength is a _____ If Electromagnetic Radiation A has a lower frequency than B, which wavelength is longer?

distance between corresponding points on adjacent waves. distance unit (meters, centimeters, or nanometers) A is longer

The columns in the periodic table are referred to as _______

groups.​

alkali metals (group 1)

lithium, sodium, potassium, rubidium, cesium, and francium In their pure state, all of the alkali metals have a silvery appearance and are soft enough to cut with a knife. However, because they are so reactive, alkali metals are not found in nature as free elements. They combine readily with most nonmetals. And they react vigorously with water to produce hydrogen gas and aqueous solutions of substances known as alkalis. Because of their extreme reactivity with air or moisture, alkali metals are usually stored in kerosene. Proceeding down the column, the elements of Group 1 melt at successively lower temperatures.

The groups and periods of the periodic table display general trends in the following properties of the elements: electron affinity, electronegativity, ionization energy, atomic radius, and ionic radius. •

memorize picture

The chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons is called

metallic bonding.

atomic radius How does radii size change as you move across a period?

one-half the distance between the nuclei of identical atoms that are bonded together Atomic radii decrease as you move from left to right across a period As atomic # increases, atomic radius increases

Schrödinger wave equation

originally applied to the hydrogen atom, it led to the quantum mechanical model of the atom • Quantization of electron energies is a natural outcome of the Schrödinger wave equation, which describes the properties of an atom's electrons.

The rows in the periodic table are called _______________

periods.

Ionic vs covalent

see photo

The electrons in an atom that are available to be lost, gained, or shared in the formation of chemical compounds are referred to as ___________ electrons.

valence electrons.

4.3 Electron configurations - main ideas

• The ground-state electron configuration of an atom can be written by using the Aufbau principle, Hund's rule, and the Pauli exclusion principle. • Electron configurations of some atoms, such as chromium, deviate from the predictions of the Aufbau principle, but the ground-state configuration that results is the configuration with the minimum possible energy.

How do electrons move?

• When an electron moves from an excited state to ground state, a photon is emitted. The photon's energy equals the energy difference between the two levels. • An electron in an atom can move from one main energy level to a higher main energy level only by absorbing an amount of energy exactly equal to the difference between the two levels.

Why Do Chemical Bonds Form? 2 ways

1) Complete an Octet (achieve stable noble gas electron configurations); 2) Decrease the number of particles that are whizzing around

Hund's rule

1) all orbitals of equal energy are occupied by one electron before any orbital is occupied by a second electron, and 2) all electrons in singly occupied orbitals must have the same spin

Orbital How many electrons can an orbital hold?

A 3D region around the nucleus where an electron is most likely to be found. (orbital=probability function) Electrons exist in orbitals - location and movement can never be exactly known, approximated with probability function Electrons DO NOT circle the nucleus like planets circle the sun. DO NOT orbit, exist in orbitals TWO - regardless of size/shape of orbital.

polar covalent bond

A covalent bond in which electrons are not shared equally resulting in an uneven distribution of electrical charge.

electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound. Atoms that want to gain electrons to achieve greater stability have HIGH Electronegativities Atoms that want to lose electron to achieve greater stability have LOW Electronegativities. The highest possible electronegativity is 4.0.

A molecule is a neutral group of atoms that are held together by covalent bonds. A chemical compound whose simplest units are molecules is called a molecular compound.​

A molecule may consist of two or more atoms of the same element, as in oxygen, or two or more different atoms, as in water or sugar

anion

A negatively charged ion The formation of an anion by the addition of one or more electrons always leads to an increase in atomic radius. This is because the total positive charge of the nucleus remains unchanged when an electron is added to an atom or an ion. So the electrons are not drawn to the nucleus as strongly as they were before the addition of the extra electron. The electron cloud also spreads out because of greater repulsion between the increased number of electrons

photon

A photon is a particle of electromagnetic radiation having zero mass and carrying a quantum of energy. The energy of a photon depends on the frequency of the radiation (Ephoton = hν).​

cation

A positively charged ion The formation of a cation by the loss of one or more electrons always leads to a decrease in atomic radius, because the removal of the highest-energy-level electrons results in a smaller electron cloud. Also, the remaining electrons are drawn closer to the nucleus by its unbalanced positive charge.

quantum

A quantum of energy is the minimum quantity of energy that can be lost or gained by an atom. the basic unit of electromagnetic energy; it characterizes the wave properties of electron

Compare/Contrast properties of : Alkali metals Alkaline-earth metals Transition metals

All three are metals Alkali & Alkaline-earth are so reactive that they are not found in nature as free elements. Transition elements are less reactive - found in nature as free elements. Transition elements do not form compounds easily because they are less reactive

ion

An ion is an atom or group of bonded atoms that has a positive or negative charge. Sodium, for example, forms an Na+ ion.

ionization

Any process that results in the formation of an ion is referred to as ionization.

6.1 - Main Idea

Atoms form chemical bonds by gaining, losing or sharing electrons.​

How is the periodic table organized?

By Properties/Atomic #s elements are arranged in order of their atomic numbers so that elements with similar properties fall in the same column.

Multiple atoms can bond covalently to form a single ion.

Certain atoms bond covalently with each other to form a group of atoms that has both molecular and ionic characteristics. A charged group of covalently bonded atoms is known as a polyatomic ion. Polyatomic ions combine with ions of opposite charge to form ionic compounds.

Bonding and Electronegativity

Check out the difference in eletronegativities to determine "Bond Character" (Photo) Differences in electronegativity reflect the character of the bonding between the elements Electronegativity of more electromagnetic element - electronegativity of less electromagnetic element the greater the difference, the more ionic the bond is For example, the electronegativity difference between fluorine, F, and cesium, Cs, is 4.0 - 0.7 = 3.3. So, according to Figure 1.2, cesium-fluorine bonding is ionic. Fluorine atoms, which are highly electronegative, gain valence electrons, causing the atoms to become anions. Cesium atoms, which are less electronegative, lose valence electrons, causing the atoms to become cations.​

When electrons change energy states, the amount of energy given off or absorb is equal to _____

E = hv

What is the equation that relates the speed, wavelength, and frequency of electromagnetic radiation

E=hv E is the energy, in joules, of a quantum of radiation ν is the frequency of the radiation emitted, h is Planck's constant; h = 6.626 × 10-34 J • s

How are electron affinity and electronegativity related?

Electron affinity measures how easily an atom gains electrons. Electronegativity measures the ability of an atom to attract electrons. Therefore, atoms with a high negative electron affinity are the most electronegative.

How are groups of atoms held together?

Electrostatic Attraction both nuclei repel each other both electron clouds repel each other the nucleus of one atom attracts the electron cloud of the other atom and vice versa

ionic bond

Formed when one or more electrons are transferred from one atom to another results from the electrical attraction between cations and anions

Max Planck

German physicist who developed quantum theory and was awarded the Nobel Prize for physics in 1918. Figured out that electromagnetic energy in quantized - for a given frequency of radiation (or light), all possible energies are multiples of a certain unit of energy, called a quantum. Energy changes do not occur smoothly but rather in small specific steps

Periodic Table groups - what are they?

Group 1, alkali metals; Group 2, alkaline earth metals; Groups 3-12, transition metals; Group 13-16, non-metals/metaloids Group 17, halogens; Group 18, noble gases.

What are the exceptions to the lewis structure octet

H=2 Be=4 B=6 P=10 S=12

The ions in an ionic compound lower their potential energy by forming an orderly, three-dimensional array in which the positive and negative charges are balanced. The electrical forces of attraction between oppositely charged ions extend over long distances, causing a large decrease in potential energy.​

Ions and Electrical Forces In an ionic crystal, ions minimize their potential energy by combining in an orderly arrangement known as a crystal lattice

what is the dual wave-particle nature of light

Light exhibits many wavelike properties, but it can also be thought of as a stream of particles. True for all electromagnetic radiation Electrons have properties of both particles and waves -> De Broglie hypothesis

6.4 Metallic Bonding

Main Idea: Metal electrons move freely in empty, overlapping orbitals.

Metallic bond strength

Metallic bond strength varies with the nuclear charge of the metal atoms and the number of electrons in the metal's electron sea. Both of these factors are reflected in a metal's enthalpy of vaporization. The amount of energy as heat required to vaporize the metal is a measure of the strength of the bonds that hold the metal together. The enthalpy of vaporization is defined as the amount of energy absorbed as heat when a specified amount of a substance vaporizes at constant pressure

Some atoms can share multiple pairs of electrons. Double and triple bonds are referred to as what

Multiple covalent bonds single bond: one pair of electrons share between two atoms double bond: two pairs of electrons are shared between two atoms. triple bond: three pairs of electrons are shared between two atoms.

NO BED for Chemistry Students

N - determine the total Number of valence electrons available for bonding. O - "Odd" (different) atom in the middle.Usually C, S, Si etc. B - Bond everything with single bonds. E - Add Electrons to fill out all atom's octets. D - Determine number of electrons used.Double or triple bond as necessary to decrease the number of electrons used.

refers to bonding in molecules or ions that cannot be correctly represented by a single Lewis structure.

Resonance

valence electron

The electrons available to be lost, gained, or shared in the formation of chemical compounds are referred to as valence electrons. Valence electrons are often located in incompletely filled main-energy levels. For example, the electron lost from the 3s sublevel of Na to form Na+ is a valence electron. Electrons on the outermost energy level of an atom