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