Chem test 3
wavelength
(symbolized by the Greek letter lambda,) is the distance between two consecutive waves -meausrement of crest to crest or trough to trough -determines what type of light we have -meter is its unit
the various types of electromagnetic radiation and important info about them
(x-rays, microwaves, and so on) differ in their wavelengths. notice that X rays have very short wavelengths, whereas radiowaves have very long wavelengths Right to left on electromagentic spectrum: wavelengths goes from biggest to smallest, frequency goes from lowest to highest therefore wavelength and frequency are inversely related -this means that the electromagnetic radiations that have higher frequencies on the left of the electromagnetic spectrum have short wavelengths and lower frequencies have longer wave lengths, why is that?
Another important thermodynamic concept is spontaneity
-A spontaneous process is one that will occur in a system without outside input under a given set of conditions -A nonspontaneous process requires external action to proceed
properties of metals
-Have a lustrous appearance -Conduct electricity and heat -Malleable and ductile -Metals tend to lose electrons to form cations
ionic compounds/substances
-Ionic compounds are made of ions -Attraction between anions and cations keeps them together -We call these ionic bonds -when a metal and a nonmetal react, one or more electrons are transferred from the metal to the nonmetals to give ionic bonding -formed when an atom that loses electrons relatively easily reacts with an atom that has a high affinity for electrons. in other words, an ionic compound results when a metal reacts with a nonmetal
ionization energy
-Ionization energy is the amount of energy required to remove an electron from an atom -Removing the first electron is the first ionization energy, removing another is the second ionization energy, etc. -Second and higher ionization energies are always larger (more endothermic) than first ionization energies -Ionization energy increases across a row(period) of the periodic table and decreases down a group The ionization energy of an atom is the energy required to remove an electron from an individual atom in the gas phase. As we have noted, the most characteristic chemical property of a metal atom is losing elec- trons to nonmetals. Another way of saying this is to say that metals have relatively low ionization energies, a relatively small amount of energy is needed to remove an elec- tron from a typical metal. Recall that metals at the bottom of a group lose electrons more easily than those at the top. In other words, ionization energies tend to decrease in going from the top to the bottom of a group. -In contrast to metals, nonmetals have relatively large ionization ener- gies. Nonmetals tend to gain, not lose, electrons. Recall that metals appear on the left side of the periodic table and nonmetals appear on the right. Thus it is not surprising that ionization energies tend to increase from left to right across a given period on the periodic table. -ionizattion energies generally increase across a period. energy required to remove an electron increases across a period -In general, the elements that appear in the lower-left region of the pe- riodic table have the lowest ionization energies (and are therefore the most chemically active metals). On the other hand, the elements with the highest ionization energies (the most chemically active nonmetals) occur in the upper-right region of the periodic table.
energy units
-Joule -cal -kilocalorie
lewis symbols
-Lewis symbols are the single atom or ion representation of valence electrons • Remember: valence electrons are the electrons in the highest principal energy level Example: Carbon with four dots around it (four valence electrons)
lewis symbols of ions
-Lewis symbols of ions usually have either eight valence electrons or none (for metals it will just be the symbol in brackets with the charge outside of it)(for nonmetals, it will be the eight valence electrons around the symbol inside of brackets with charge on the outside). if it's 1- charge, you just put -. -To draw the Lewis symbol of an ion: -Draw the Lewis symbol of the atom -Take away the electrons equal to a positive charge -Add the electrons equal to a negative charge -Put the chemical symbol and dots in brackets with the charge as a superscript
lewis structures of covalent compounds: polyatomic ions
-Polyatomic ions are drawn with a combination of covalent and ionic rules, as they are ions with covalent bonds! -They have bonding pairs and a structure that looks covalent with brackets and the charge indicated in superscript
lewis structures of covalent compounds: lewist structures
-Remember: Lewis structures are combinations of Lewis symbols that show the structure and bonding of atoms in a molecule -Remember: elements generally bond until they achieve a full valence shell (an octet) • One exception we need to know: boron makes three bonds
state functions
-State functions must have their state defined The standard state of a solid or liquid substance is the pure substance at 1 bar pressure -The standard state of a gas is the pure gas behaving as an ideal gas at a pressure of 1 bar -The standard state of an aqueous solution is at a concentration of 1 M and at 1 bar pressure
frequency
-Symbol is v -unit is Hertz (Hz) or inverse seconds (s^-1) The frequencyof the wave (symbolized by the Greek letter nu,) indicates how many wavepeaks pass a certain point per given time
first law of thermodynamics
-The First Law of Thermodynamics states that energy can be converted from one form to another, but cannot be created or destroyed -The internal energy of a system (U or E) is the sum of all potential and kinetic energies in the system -A system can exchange internal energy with the surroundings through heat (q) or work (w)
bond polarity
-The polarity of a bond can be put into three rough categories • No or very little difference in EN = covalent • Moderate difference in EN = polar covalent -Large difference in EN = ionic You can estimate this difference from the position of elements on the periodic table or calculate it with Pauling electronegativity values • Even these calculations can be misleading on the boundaries
functions of state
-The state of the system is described by its temperature, pressure, and the kinds and amounts of substances present -Any property that has a unique value for a specific state is a function of state or state function -A state function does not depend on how that state was established • Path independent • Internal energy (change in U or E) is a state function
lewis structures of covalent compounds: multiple covalent bonds
-To achieve an octet, atoms must sometimes share more than one pair of electrons (more than a single bond) -Two bonding pairs creates a double bond -Three bonding pairs creates a triple bond
electron configuration of ions
-We can also predict the Lewis symbol of an ion from its electron configuration -Electrons fill to minimize their energy, and anions continue the same filling pattern as other atoms -When an atom loses electrons (forms a cation), it loses the highest principal energy level first ex: when we write, 1s, 2s, 2p
properties of nonmetals
-Wider variety of properties, mostly characterized by not having the properties of metals -Tend to gain electrons to form anions
lewis structures of ionic compounds
-a lewis structure for ionic compunds. ex:AlF3 [Al]3+, and then [F] with eight valence electrons around it and write it three times and negative charge on the outside. We can modify Lewis symbols to make Lewis structures for ionic and covalent compounds • A Lewis structure is a combination of Lewis symbols representing either transferred or shared electrons -Ionic compounds are easiest to draw, as they only involve charge neutralization -You can either think of this as the combined process of electron transfer or as a two-step process: create the correct ions, then balance their charges
lewis structures of covalent compounds: central atom
-an atom bonded to two or more atoms -The least electronegative atom is usually central -Carbon is always the/a central atom if present!
molecular compounds are made of
-discreet molecules -they share electrons thorugh covlaent bonds
potential energy
-energy resulting from condition, position,or composition - Chemical energy-potential energy stored in the bonds of chemical compounds
in 1s orbital the number stands for and the letter
-number stands for the principal energy level and s is the sublevel(type of orbital) and the shape
speed symbol and unit
-symbol is c meters per second (m/s)
kinetic energy and what is a type of kinetic energy
-the energy of a moving object -Thermal energy-kinetic energy associated with random molecular motion
atomic size/atomic radius
-the measure of the size of the atom -decreases left to right (across periods/row) -increases down the groups -The sizes of atoms vary as shown in Figure 11.36. Notice that atoms get larger as we go down a group on the periodic table and that they get smaller as we go from left to right across a period. -the large ones easily give up electrons because they're far from the nucleus. smaller ones gain b/c they're closer to the nucleus -We can understand the increase in size that we observe as we go down a group by remembering that as the principal energy level increases, the av- erage distance of the electrons from the nucleus also increases. So atoms get bigger as electrons are added to larger principal energy levels. -Explaining the decrease in atomic size across a period requires a little thought about the atoms in a given row (period) of the periodic table. Recall that the atoms in a particular period all have their outermost electrons in a given principal energy level. That is, the atoms in Period 1 have their outer electrons in the 1s orbital (principal energy level 1), the atoms in Period 2 have their outermost electrons in principal energy level 2 (2s and 2p or- bitals), and so on (see Figure 11.31). Because all the orbitals in a given prin- cipal energy level are expected to be the same size, we might expect the atoms in a given period to be the same size. However, remember that the number of protons in the nucleus increases as we move from atom to atom in the period. The resulting increase in positive charge on the nucleus tends to pull the electrons closer to the nucleus. So instead of remaining the same size across a period as electrons are added in a given principal energy level, the atoms get smaller as the electron "cloud" is drawn in by the increasing nuclear charge.
electronegavity
-the relative ability of an atom in a molecule to attract shared electrons to itself -chemists determine electronegativity values for the elements by measuring the polarities of the bonds between various atoms -note that electronegativity generally increases going from left to right across a periodi and decreases going down a group for the representative elements. -the higher the atom's electronegativity value, the closer the shared electrons tend to be to that atom when it forms a bond -noble gases are excluded from electronegativity
covalent bonding
-two identical atoms react to form a covalent bond in which electrons are shared unequally
groups are and they tell us
-vertical (up and down on periodic table) -groups tell us the number of valence electrons for the elements in that group
polar covalent bond
-when different nonmetals react, a bond forms in which electrons are shared unequally -atoms are not so different that electrons are completely transferred but are different enough so that unequal sharing of electrons results.
how do people graphically represent valence electrons or bonding structures
-with lewis structures
how to calculate how many calories are there in kJ?
-you have to convert from kJ to j b/c joule is the SI unit of energy
orbital labels
1. The number tells the principal energy level. 2. The letter tells the shape. The letter s means a spherical orbital; the letter pmeans a two-lobed orbital. The x, y, or z subscript on a p orbital label tellsalong which of the coordinate axes the two lobes l
how to write lewis symbols
1. Writethechemicalsymbol • 2. Determine the number of valence electrons • Can do this using noble-gas-core electron configurations or the group number (1A-8A notation) 3.Fill in the valence electrons around the chemical symbol • Singly first,thenpair or 1. Look at the group of the element to see how many valence electrons it has 2. put them around element
remember electron configuration for ions
1. look at periodic table to see what the ion is. ex: Ca is one group two so it's ion is Ca2+ so it has two less electrons which means the electron configuration is different than regular calcium.v
1 kilocalorie or Calorie=
1000 calories -this is the nutritional calorie on packages
list the electrons in orbitals
1s, 2s, 2p (s,s,p) 3s, 3p, 4s 3d, 4p, 5s 4d, 5p, 6s 4f, 5d, 6p 7s, 5f, 6d 7p
if questions asks for the maxinum number of electrons in each of the p orbitals, it's
2 because 2 times 3 equals 6
1 calorie=
4.184 J (given on test)
if it's asking for the maxinum number of electrons in the p sublevel of the third principal level, it's
6, so if it's asking for the p, s, or d sublevel electrons, it 2, 6, or 10
formula for heat capacity
C= q/change in T
Energy equals
Change in E= q+w (heat plus work) (if it ever says gas releaes 679J of heat, that means it lost that heat so it's negative)
lewis structures of covalent compounds defined
Covalent bonds involve the sharing of electrons to achieve a full valence shell (usually an octet)
electromagnetic radiation
Electromagnetic radiation is energy transmitted when electric and magnetic fields are propagated as waves through space -travels as waves
metalloids have
Have a mixture of metal and nonmetal properties
path dependent functions
Heat and work are functions that depend on the path taken when a system undergoes a change
Heat (q)
Heat is the one that's in joules in the problem, it's basically the heat of energy you could say.so if it's asking something about heat, like how much heat is gained or lost, it's talking about heat and you just solve for Q. -Heat is the transfer of thermal energy between a system and surroundings due to a temperature difference -The amount of heat (q) needed to change the temperature of a substance depends on -How much the temperature changes -The quantity of the substance -The nature of the substance
why are the most chemically active elemtns in the lower left portion of the periodic table and the upper right
Ionization energies generally increase in going from left to right across a given period. Thus, the elements that appear in the lower left-hand region of the periodic table have the lowest ionization energies (and are therefore the most chemically active metals), while the elements that occur in the upper right-hand region of the periodic table have the highest ionization energies (and are thus the most chemically active nonmetals).
The SI unit of energy is the
Joule(J): kg, m^2, s^-2 (look in notes b/c i think i have more about this)
as the level number increases in an orbital
One important characteristic of orbitals is that as the level number in-creases, the average distance of the electron in that orbital from the nucleusalso increases. That is, when the hydrogen electron is in the 1 s orbital (theground state), it spends most of its time much closer to the nucleus thanwhen it occupies the 2s orbital (an excited state)
if you want to represent polar covalent bonds with their symbols
S+ goes with the less electronegative element S- goes with the more electronegative element
change in temperature equals
Tf-T1
enthalpy of reaction
The enthalpy of reaction (Hrxn) is the enthalpy change per mole of reaction • Most common unit is kJ/mol -Remember: one mole of reaction is dependent on the reaction coefficients -These enthalpies of reactions can be used to relate the amount heat released to a certain amount of a substance when it's reacted
ground state
The lowest possible energy state of an atom is called
define heat capacity
The quantity of heat required to change the temperature of a system by one degree is the heat capacity (C)
lewis structures of covalent compounds: steps to drawing lewis structures
There are four steps to drawing a basic Lewis structure -Determine total number of valence electrons -Identify the central and terminal atoms -Draw a skeletal structure with single bonds -• Subtract two electrons from the total valence for each single bond • With the remaining valence electrons, complete the octet of all terminal atoms and attempt to fill in the octet of central atoms -If the central atoms have an octet after this step, you're done! -Otherwise, convert lone pairs on terminal atoms into double or triple bonds until every atom has an octet
lewis structures of covalent compounds: bonding pair
Two electrons shared between two atoms are called a bonding pair • The dots of bonding pairs are often replaced by lines
lewis structures of covalent compounds: lone pair
Two electrons that are only on one atom (not involved with bonding) are called a lone pair
Frequency symbol and unit
V=symbol Hertz (Hz) or inverse seconds (s^-1)
waves are
Waves are a disturbance that transmits energy through space
the sub levels
We divide the princi-pal levels into various numbers of sublevels. Principal level 1 consists of onesublevel or orbital, principal level 2 has two sublevels, principal level 3 has three sub-levels, and principal level 4 has four sublevels
when hydrogen atoms
When a hydrogen atom absorbs energy from some outside source, ituses this energy to enter an excited state. It can release this excess energy (goback to a lower state) by emitting a photon of light (Figure 11.9). We can pic-ture this process in terms of the energy-level diagram shown in Figure 11.10.The important point here is that the energy contained in the photon correspondsto the change in energy that the atom experiencesin going from the excited stateto the lower s
what forms a covalent bond
When two elements bond covalently, but they have a large electronegativity difference (EN), they form a polar covalent bond -Polar covalent bonds involve the unequal sharing of electrons -They result in partial charges -We can use electrostatic potential maps to visualize the electron distribution other info: -Ionic and covalent bonds are two ends of a spectrum, rather than a binary choice -Some elements are more electronegative - attract electrons more strongly - than others
bond
a force that holds groups of two or more atoms together and makes them function as a unit.
Notice as you compare levels 1, 2, and 3 that
a new type of orbital (sub-level) is added in each principal energy level. (Recall that the p orbitals areadded in level 2 and the d orbitals in level 3.) This makes sense because ingoing farther out from the nucleus, there is more space available and thusroom for more orbitals
lewis structures of covalent compounds: skeletal structure
all atoms arranged in the order in which they bond to each other
excited hydrogen atoms
alwasy emit photons with the same discrete colors (wavelengths). they never emit photons with eergies (colors) in between those shown.
lewis structures of covalent compounds: terminal atom
an atom bonded to only one other atom • Hydrogen atoms are always terminal
anions get
bigger as they receive electrons
an excited atoms release some or all of its excess energy by
by emitting a photon (a "particle" of electromagnetic radiation) and thus move to a lower energy state.
you can convert between frequency and wavelength with formula
c= v times wavelength
closed system
can exchange energy, but not matter with its surroundings
isolated system
cannot exchange energy or matter with its surroundings
different wavelengths of light
carry different amounts of energy per photon
hydrogen atoms must have as well as oll other atoms/elements
certain discrete energy levels
components of waves are
crest, amplitude, trough, and wavelength
transitions metals filled with electron sub levels
d
list types of energy
energy work kinetic energy potential energy
what is the most electronegative element
fluorine
work is
force acting over a distance
what is the least electronegative element
francium
open system
freely exchanges energy and matter with its surroundings
elements have the same chemical properties if they
have the same number of electrons in their outer energy levels
endothermic
heat enters system from surroundings
exothermic
heat leaves system from surroundings
a higher amplitude means
higher light -In a sense, the amplitude is the distance from base to crest
crest
highest surface part of the wave
the size of the sphere of an orbital
increases as n (the number) increases
an atom with excess energy
is in an excited state
heat gained by the system
is lost by the surroundings
1s orbital
it describes the hydrogen electron's lowest energy state (the ground sta
if question asks for a given set of d orbitals consist of
it's 5 b/c 5 times 2 makes 10
the 2s orbital is
larger in size than 1s orbital. ). The three 2p orbitals are not spherical but have two"lobes.
trough
lowest part of the wave
wavelength unit (look up symbol, it looks like upside down tree branch)
meter (m)
when things/surroundings go out of the system, it's
negative
what are the three types of system
open closed isolated
groups 1a through 8A are filled with electron sub levels
p
System
part of the universe chosen to study
the energy contained in the photon
photon corresponds to the change in energy that the atom experiencesin going from the excited stateto the lower state
when things/surroundings go into the system, it's
positive
q will be positive if heat is (fill in blank) and (fill in blank)
q will be positive if heat is gained and negative if heat is lost
We usually use molar or specific heat capacity! The heat capacity per mole or gram of a substance at a constant pressure
q= mass,heat capacity, change in temperature -mass has to be in grams, so you may have to convert if it's not given in grams. they may give you the density. if they do, you use that to convert. it should be in grams. it would be 1 mL equals the amount given and you would multiply by the mL in problem to get grams.
we can conclude that all energy levels of hydrogen are/ as well as other elements
quantized. That is, only certain values are allowed. Scientists have foundthat the energy levels of all atoms are quantized
order of electromagnetic spectrum from right to left
radio, microwave, infrared, ultraviolet, x-rays, gamma rays
frequency decreases from and increases from so this means
right to left left to right Gamma rays have the highest frequency(10^-16) and radio waves have the lowest frequency violet light has highest frequency red had the lowest
groups 1 and 2 are filled with electron sub levels
s
cations get
smaller and smaller the more electrons they give up
1s and 2s orbitals are both
spherical
each discrete energy level is subdivided into
sublevels
energy is
the capacity to do work, or produce heat.
the more protons,
the larger the atom b/c the electrons can spread out
the longer the wavelength of light
the lower the energy of its photons
oribital
the probability map for an electron
surroundings
the rest of the universe
the less protons
the smaller the atom b/c electrons are packed closely together b/c of protons in nucleus(the positive charge)
law of conservation of energy
the total energy of the universe remains constant; energy is neither created nor destroyed
principal energy levels
these are the discrete energy levels and you label them with integers
when atoms receive energy from some source they become
they become excited—they can release this en-ergy by emitting light. The emitted energy is carried away by a photon. Thusthe energy of the photon corresponds exactly to the energy change experi-enced by the emitting atom. High-energy photons correspond to short-wavelength light and low-energy photons correspond to long-wavelengthlight. The photons of red light therefore carry less energy than the photonsof blue light because red light has a longer wavelength t
the speed of light is constant in a
vacuum: 3.00 times 10^8 ms^-1
Which color of visible light has the most energy per photon?
violet light because it has the highest frequency
bond energy
we can obtain information about the strength of a bond by measuring the energy required to break the bond
enthalpy
• Enthalpy(H) is the change in energy of a system at constant pressure, the sum of the change in internal energy and the pressure-volume product -For a constant pressure process, the change in enthalpy (change in H) is equal to the heat exchanged •Positive in an endothermic reaction •Negative in an exothermic reaction -The enthalpy change is often called "the heat of" -Enthalpy is one of the most used concepts in thermodynamics
lewis symbols and bonding
• Lewis symbols can show how many bonds an atom will usually form • Atoms tend to ionize until they achieve the valence electron configuration of a noble gas (ns2np6) -They will also bond to achieve this configuration -This is also called the octet rule -An atom can form two types of compounds -Covalent compound - electrons are shared through bonds -Ionic compound - electrons are completely transferred, and only electrostatic forces keep the ions together -The Lewis symbol shows how many bonds must be formed to achieve an octet
