JLH Chem 2nd pp Flashcards
Elements
pure substances
can’t be broken down to a simpler pure
substance by a chemical reaction.
Most are naturally occurring
Most elements are monoatomic. What does this mean?
Only 1 atom
(noble gases are all monatomic)
Some elements are polyatomic. What does this mean?
contains more than one atom
Examples: N2, Cl2, O2, O3, S8, diamond
Element names for:
Copper
Gold
Iron
Copper: Cu
Gold: Au
Iron: Fe
Element names for
Lead
Mercury
Potassium
Lead: Pb
Mercury Hg
Potassium K
Potassium K
Element names for
Silver
Sodium
Tin
Silver: Ag
Sodium: Na
Tin: Sn
What 4 elements are called the building block elements since they make up 96% of living organisms?
Carbon (C)
Oxygen (O)
Nitrogen (N)
Hydrogen (H)
What are the Major minerals (macronutrients)?
Potassium (K)
Phosphorus (P)
Sodium (Na)
Sulfur (S)
Chlorine (Cl)
Calcium (Ca)
Magnesium (Mg)
Make up .1-0.2% of elements
Trace elements (micronutrients)
Copper (Cu)
Fluorine (F)
Iodine (I)
Iron (Fe)
Nickel (Ni)
Zinc (Zn)
and more
Compound
formed when you chemically combine two or more elements
NaCl
H2O
C8H18
C8H18
Atom
smallest basic unit of an element
What are the 3 subatomic particles?
Protons
Neutrons
Electrons
The quantities and location of these subatomic particles in the atom are responsible for the properties of the element
Protons (p)
Positive 1 charge
Mass of 1 amu (atomic mass unit)
Located in nucleus
Defines the element (each element has a different # of protons)
Neutron
No charge
Mass of 1 amu
located in the nucleus
acts as “atomic glue”, keeping nucleus together (protons repel each other)
Electron (e-)
Negative 1 charge
about 2000x smaller than p & n
located in electron cloud that surrounds nucleus
responsible for chemical reactions & balancing proton charge
Why do the electrons move around the nucleus?
The negatively charged electrons are attracted to the positively charged protons (opposites attract).
What is the comparative size between the nucleus and electron cloud?
The nucleus is very small compared to the electron cloud.
If the nucleus was a marble, the atom would be the size of the Superdome!
Atoms are tiny (~1 x 10^-24 g) and can’t be measured directly by instruments. We measure mass relative to one another using what as a reference?
Carbon-12 (C-12)
1 atomic mass unit (amu) is equal to exactly 1/12 the mass of a C-12 atom.
1 amu =
1.66x10^-24 g
Protons and neutrons both have masses of ~ 1 amu.
An element has a given number of what in each atom?
Protons
All C atoms have 6 protons, All H atoms have 1 proton, etc.
(Z number)
Atomic number
the number of protons in an atom
Mass number (A)
protons + neutrons
What can we determine if we have both the Z number and A number?
Can determine number of protons, neutrons and electrons
number of e─ = number of protons
All elements of an atom have same number of what?
protons
Can the number of neutrons vary?
yes.
This is why we have isotopes.
- Uranium isotopes*
- Both have 92 protons*
How similar are isotopes usually?
Generally the properties of isotopes are identical.
Sometimes one isotope is radioactive.
Sometimes one isotope is radioactive.
Used as diagnostic tool and for medical treatments
I-131 (iodine 131)
How is the mass of molecules calculated?
calculated by adding masses of individual atoms
H2O:
2H= 2(1.008amu) +
O= (16.00amu) =
18.02 amu
Groups of periodic table
vertical columns
(these elements have similar properties)
main group elements
(representative elements)
the elements in groups 1, 2, and 13 through 18 of the periodic table
Transition metals
groups 3-12
inner transition elements
lanthanides and actinides
nonmetals on the periodic table
elements to the right of metalloids
metalloids
Elements that have properties of both metals and nonmetals.
some characteristics of metals
Shiny
Good conductors
Mostly solids
Give up electrons to form compounds with non-metals
some characteristics of non-metals
Not shiny
Not good conductors
Often polyatomic
Solids liquids and gases
Take additional electrons to form compounds with metals or “share electrons” with other non-metals
some characteristics of nobel gases
Monoatomic
Unreactive
Electron clouds are not random. Explain a little more.
Electrons confined to specific area
Discreet energy levels
What are the shells of an atom?
Specific energy levels
n= 1,2,3,4 etc.
The path of an electron around the nucleus of an atom (orbit)
What shells fill first?
lower shells
What are shells broken down into?
subshells
s, p, d, f
Each subshell contains what?
orbitals
How many electrons can an orbital have?
2 max
Electron configuration
1s 2s 2p 3s 3p
What do we use to determine total electrons?
Z (atomic number)
Fe has 26 electrons. What is the electron configuration?
1s2
2s2
2p6
3s2
3p6
4s2
3d6
What is the maximum number of valence electrons?
8
except H & He- max is 2
Periodic trend
properties that change in a regular way across a row or down a column
Ionization Energy
The energy needed to remove an electron from a neutral atom
Electronegativity
the ability of a bonded atom to pull the electrons toward it.
Think of it as the attraction between the nucleus and the valence electrons.
Both ionization energy and electronegativity are a measure of the atom’s ability to do what?
hold on to it’s electrons.
Metals on left side of chart
Low ionization energy/electronegativity.
Few “dots”.
Easier to give up 1 or 2 electrons than gain 6 or 7.
This explains why metals give up electrons to form compounds
Non-metals on the right
High Ionization energy/electronegativity.
High number of “dots”
Easier to take a couple of electrons than to give up a bunch.
This explains why non-metals take electrons to form compounds.
Atomic size
distance between nucleus and outer edge of valence shell
Increases as you go down periodic chart.
Number of electrons increasing so more shells
Decreases as you go from left to right.
Atoms toward right are holding the electrons tighter (leading to smaller radius)
How many elements are currently known?
118 elements
How many elements are naturally occurring?
90 elements are naturally occuring
28 have been prepared by scientists in a lab
Carbon Monoxide (CO) is formed in small amounts during what?
combustion of fossil fuels like gasoline.
CO: Carbon and oxygen
what is Rn?
Radon (noble gas)
radioactive gas produced in the soil
what is the main component of the earth’s atmosphere?
Nitrogen (N)
3 categories of periodic table
metals, nonmetals, metalloids
All metals are solid at room temperature except what?
mercury (liquid)
what non-metal is liquid at room temperature?
Bromine
What are the 7 metalloids?
Boron (B)
Silicon (Si)
Germanium (Ge)
Arsenic (As)
Antimony (Sb)
Tellurium (Te)
Polonium (Po)
boring silly germs are ants telling politics
What are the elements that form water?
Oxygen and Hydrogen
What elements are found in the proteins, carbs, lipids, and nucleic acids?
Carbon
Hydrogen
Oxygen
nitrogen is found in proteins & nucleic acids
What macronutrients are found in our body fluids?
Potassium
Chlorine
Sodium
What macronutrient is found in all nucleic acids?
Phosphorus
At least how much of each macronutrient is needed in the daily diet
100 mg of each
Trace elements (micronutrients) are needed in the daily diet in small quantities, usually less than what?
15mg
2H2 + O2 → 2H2O
Coefficients (2) & subscripts (2)
What color sphere is used for the element oxygen?
Hydrogen?
O2: Red
H: Gray
What color sphere is used for the element Carbon?
Nitrogen?
C: Black
N: Blue
What color sphere is used for the element Chloride?
fluorine?
chloride (Cl): green
fluorine (F): yellow
What elements are in NaCN?
1 sodium (Na)
1 carbon (C)
1 nitrogen (N)
All matter is composed of the same basic building blocks called what?
atoms
most of the mass of an atom resides where?
nucleus
what comprises most of the volume of an atom?
electron cloud
because the mass of an individual atom is so small, chemists use a standard mass unit called what?
Atomic mass unit (amu)
What is the isotope hydrogen, with one neutron and one proton (mass number=2), called?
Deuterium (D)
What is the isotope hydrogen with a mass number = 3 called?
tritium (T)
Determine the number of neutrons in the isotope carbon-14
Since carbon’s atomic number (Z) is 6 we just subtract 6 from 14 = 8 neutrons
How do we determine the atomic weight of isotopes?
1: find amu of each & their abundance (75.78%)
2: multiply amu by percent (for each)
3: add the answers
What is the atomic weight of copper:
2 isotopes
copper-63 (62.93 amu, 69.17%)
copper-65 (64.93 amu, 30.83%)
63.546 u
iodine-131 is used for
thyroid disease
iodine is a micronutrient needed by the body to synthesize what?
thyroxine
(thyroid hormone)
contains 4 iodine atoms
To evaluate the thyroid gland, a patient can be given sodium iodide (NaI) that contains radioactive iodine-131. Iodine-31 is taken up in the thyroid gland & as it emits radiation, it produces an image in a thyroid scan.
who created the periodic table?
Dmitri Mendeleev (1869)
Elements in the same row (period) in the periodic table are similar in what way?
size
A column in the periodic table is called a group. What do elements in the same group have similar?
similar electronic & chemical properties
How many rows are on the periodic table?
7
what do the lanthanides begin with?
Cerium (Z=58)
after lanthanum (La)
what do the actinides begin with?
Thorium (Z=90)
after actinium (Ac)
What is 1A-8A groups?
1, 2, & 13-18
(main groups)
what is 1B-8B?
3-12
(transition metal elements)
Alkali metals are in group 1A. Hydrogen is in group 1A, is it an alkali metal?
no
What are the alkali metals?
Lithium
Sodium
Potassium
Rubidium
Cesium
Francium
Like some pork roast cooked fresh
characteristics of alkali metals
soft, shiny, low melting points
good conductors
react readily with water to form basic solutions
What are alkaline earth metals?
Beryllium
Magnesium
Calcium
Strontium
Barium
Radium
buried magazines can still be read
None of the metals in groups 1A & 2A exist in nature as pure elements; rather, they are always combined with other elements to form compounds. What are some examples of compounds formed from 1A?
NaCl
KI (potassium iodide)
None of the metals in groups 1A & 2A exist in nature as pure elements; rather, they are always combined with other elements to form compounds. What are some examples of compounds formed from 2A?
Magnesium sulfate (MgSO4)
barium sulfate (BaSO4)
what are the halogens?
fluorine (F)
Chlorine (Cl)
Bromine (Br)
Iodine (I)
Astatine (At)
find chief Brom in Alaska
In their elemental form, halogens contain what?
2 atoms joined together
Cl2, Br2, & I2
Are halogens reactive?
very reactive
combine with many other elements to form compounds
what halogens are gases at room temperature?
fluorine
chlorine
which halogen is liquid at room temp?
bromine
what halogen is solid at room temp?
iodine
what are the noble gases?
helium (He)
Neon (Ne)
Argon (Ar)
Krypton (Kr)
Xenon (Xe)
Radon (Rn)
he’ll need Argon, Krypton, Xenon & Radon
How do elements in a group of the periodic table have similar chemical properties?
The chemical properties of an element are determined by the number of electrons in an atom.
the modern description of the electronic structure of an atom is based on what principles?
Electrons do not move freely in space; rather, an electron is confined to a specific region, giving it a particular energy.
Electrons occupy discrete energy levels. The energy of electrons is quantized; that is the energy is restricted to specific values.
The electrons that surround a nucleus are confined to regions called what?
principal energy levels or shells
1s
The number of electrons that can occupy a given shell is determined by what?
value of n
The farther a shell is from the nucleus, the ______ its volume becomes, and the ____ _________ it can hold.
The farther a shell is from the nucleus, the larger its volume becomes, and the more electrons it can hold.
how many electrons can the first, second and third shells hold?
1st: 2
2nd: 8
3rd: 18
* max # of e- is given by the formula 2(n^2)*
Orbital
region of space where the probability of finding an electron is high.
Each orbital can hold 2 electrons
The two electrons in an orbital must have ________ spins.
The two electrons in an orbital must have opposite spins.
A particular type of subshell contains a specific number of orbitals. How do we figure out how many orbitals each subshell contains?
S = l-0
P = l-1
D = l-2
F = l-3
l-0 = 0 (1 orbital)
l-1 = -1, 0, +1 (3 orbitals)
l-2 = -2, -1, 0, 1, 2 (5 orbitals)
l-3 = -3, -2, -1 0, 1, 2, 3 (7 orbitals)
The first shell of electrons around a nucleus (n=1) has only one s orbital, called the 1s orbital because it is in the first shell. What (type of) orbitals does the 2nd shell of electrons have?
2 types:
1 s orbital (2s)
3 p orbitals (2px, 2py, 2pz)
called 2s & 2p orbitals because they are located in the second shell.
The 3rd shell of electrons (n=3) has how many orbitals?
3 types:
1 s orbital
3 p orbitals
5 d orbitals
(3s, 3p, 3d)
The maximum number of electrons that can occupy a shell is determined by what?
the number of orbitals in the shell.
Shapes of orbitals
s orbital:
sphere
p orbital:
peanut
d orbital:
donut
All s orbitals are spherical, but what happens when the shell number increases?
the orbital gets larger
The 3 p orbitals in a shell are what to each other along the x, y, & z axes?
perpendicular
What is the lowest-energy arrangement of electrons called?
ground-state
What are 3 rules to determine the ground-state electronic configuration of an atom?
1) electrons are placed in the lowest-energy orbitals beginning with the 1s orbital
2) Each orbital holds max of 2 electrons
3) When orbitals are equal in energy, one electron is added to each orbital until the orbitals are half-filled, before any orbital is completely filled.
orbital diagram
box = orbitals
arrows = electrons
In an orbital diagram, a single electron is called what?
unpaired electron
(single arrow pointing up)
the 4s orbital is filled with electrons before the 3d orbitals because it is lower in energy.
4s = 4+0 = 4
3d = 3+2 = 5
What does the orbital diagram for Hydrogen look like?
Helium?
Hydrogen: 1s^1
(shell 1, s subshell, 1 electron)
Helium: 1s^2
(shell 1, s subshell, 2 electrons)
Lithium has 3 electrons on period 2, group 1. how many electrons are in the ground state?
2 electrons are in the 1s orbital.
The remaining electron is an unpaired electron in the 2s orbital
1s2 2s1
Oxygen has 8 electrons. In the ground state, 2 electrons are added to both the 1s & 2s orbitals. The remaining 4 electrons must be distributed among what?
the 3 2p orbitals to give the lowest-energy arrangement.
How can we shorten the electronic configuration for carbon from 1s2 2s2 2p2?
He 2s2 2p2
use the name of the noble gas from the preceding row and add the remaining orbitals & subscripts
What groups does the s block consist of?
groups 1A & 2A & helium
What groups does the p block consist of?
groups 3A-8A (except helium)
What does the d block consist of?
the 10 columns of transition metals
What does the f block consist of?
The 2 groups of 14 inner transition metals.
how do you draw an orbital diagram for the ground-state electronic configuration of sulfur?
Use Z # to determine # of electrons (16)
Locate element in PTable
+ 2 electrons to each of the 1s, 2s, three 2p, & 3s orbitals (12 electrons used)
for last 4 e-
give one orbital 2 electrons & place one unpaired electron in the remaining two orbitals
What is the electronic configuration for sulfur (orbital diagram)?
Remember, when you get to the p subshell it has 3 orbitals and each one gets one electron before any get 2.
When looking at the periodic table you can look at a pair of elements as an orbital (Al & Si = 1 orbital). You can also look at each element as one space for one electron (Al would be where you would put a single electron-> up pointing arrow.) You would skip Si and put your next unpaired electron in P. After P you would go to Cl then you would go back to Si then S then Ar.
draw an orbital diagram for:
Magnesium
Aluminum
Bromine
The chemical properties of an element depend on what electrons?
most loosely held (valence)
(period number tells the number of shells;
group number tells # of valence e-)
The chemical properties of a group are similar because these elements contain the same what?
electronic configuration of valence electrons
what is the total number of electrons, valence electrons, & name of the element:
1s2 2s2 2p6 3s2 3p2
Si
14 electrons
1s2 2s2 2p6 3s2 3p2
highest shell is 3
valence electrons are in highest shell
2 + 2 = 4 V electrons
Electron-dot symbol
(Lewis dot structure)
for 1-4
v electrons, single dots are used.
With more than 4 electrons, dots are paired
What are 2 properties that illustrate periodic trends?
atomic size
ionization energy
Removing an electron from a neutral atom forms what?
cation
ionization energy is the energy needed to remove an electron from a neutral atom
In the same group, what happens with atomic number and atomic radius as we move down the column?
both increase moving down column
Does ionization energy decrease or increase moving down the column?
ionization energy decreases moving down a column
atom A is smaller than atom B.
If both atoms are in the same period, which atom has the higher atomic number?
atom A (smaller atom)
because atoms get smaller from left to right and there are more protons moving from left to right on the periodic table.
