ignore chemistry ch4

elements

pure substances from which other things are build

• cannot be broken down into simpler substances

chemical symbols

• 1-2 letter abbreviations for elements name

periodic table is organized by groups w —- propeties , and in order of increasing —- —-

similar

atomic mass

who created the periodic table?

dmitri mendeleev

groups are…

down a periodic table, vertical

periods are …

across a periodic table, horizontal

7 rows

where are the representative element?

• signified by “a”

• group 1-2, 13-`18

what are the transition elements

• stuff in the middle

• “b”

• group 3-12

from left to right the atomic number ===

increases

alkali metals

• Lithium (Li)

• sodium (Na)

• potassium (K)

halogens

chlorine (Cl2)

bromine (Br2)

iodine (I2)

metals are located where on the periodic table?

to the left of staircase

metalloids are where?

on the zigzag line, starting with Boron (B)

excluding Al

what are the macrominerals from the periodic table

needed in the body in large amounts

Ca, P, K, Cl, S, Na, Mg

• blue= macro

what are the microminerals from the periodic table

• V, Cr, Mn, Mo, Fe, Co, Cu, Zn, Si, As, Se, I

• purple

major elements in human body

H, C, N, O

orange

structure of an atom

• nucleus containing protons (+) and neutrons(0)

• the electrons (-) surround the nucelus

mass of the atom

• mass of atom is due to proton and neutron in nucleus, electrons are much smaller

• measured in amu

atpmic spectrum

when light from a heated element passes thorugh a prism, it seperates into distinct lines of color seperated by dark areas

• lines in atomic spectrum are assoc w the changes in energies of electrons

electron energy levels

• the lines in atomic spectrum are assoc w the changes in energies of electrons

• each atom has a specific energy level —> assigned values called principle quantum numbers

highest priniipal quantum number =

lower prinicpal quantum number =

why?

higher energy

lower energy

the further away you get from nucleus, more energy

energy of electron is quantized.. what does that mean ?

electrons can only have certain energy values

• energy level increases as the number gets higher

when electrons change from a lower level to a higher level…

they absorb the energy equal to the change in energy levels

when electrons change from high to lower level…

they emit energy equal to the change in energy levels

valance electrons

electrons in the outermost shell/energy level

lewis symbol

• represents valence electrons in an element

SH of water (cals) (joules)

1.00 cal g/c

4.184 J/g c

Octet rule and stability

• Chemical bonds are formed when atoms lose, gain, or share
  valence electrons to acquire an octet of eight valence
  electrons

• want to have an octet

Ionic bonds

• transfer or shared?

• melting point?

• state?

• occur when valance electrons of an atom of a metal are transferred to a nonmetal

• strong attractive forces between negative and positive ion

• high melting points

• solid at room temp

• metal+ nonmetal

How to name an ionic compound?

How to name an ionic compound?

• name of metal= first

• name of nonmetal is first syllable of nonmetal name + ide = second

• ex: magnesium bromide

Covalent Bond

• definiton

• composition

• properites

• Definition: A bond formed when two nonmetals share valence electrons to reach the magic number 8 (Octet Rule).

• Composition: Nonmetal + Nonmetal.

• Properties:

  • Lower Melting Points: They turn into liquids or gases much easier than ionic salts.

naming a covalent compound

• first= nonmetal , named by element name

• second= nonmetal, followed by ide

• when subscript indicateds 2+ atoms= use a prefix

• 1: Mono-

• 2: Di-

• 3: Tri-

• 4: Tetra-

• 5: Penta-

• 6: Hexa-

What are the metals with variable charges?

transition elements except for Zn2+, Cd2+, Ag+

• form two or more positive ions

Transition Metals & Roman Numerals

The Rule: Use Roman Numerals for Transition Metals (the middle of the table) because they can have more than one possible charge.

I - first

II - second

III - three

IV - four

V - five

polyatomic ions

• covalently bonded groups of 2+ atoms w overall charge

• “package deal”

• usually nonmetal covalently bonded to oxygen atoms

• negative charge except for ammonium (NH+4)

naming polyatomic ions

• most common polyatomic atoms end in -ate

ex: sulfate , phosphate, nitrate

• when a related ion has one less O atom= ends it -ite

ex: sulfite, phosphite, nitrite

naming compounds w polyatomic ions

• first= positive ion, usually metal

• second= name of polyatomic ion

• no prefixes used

prefixes for convalent compounds 1-10

Which three Transition Metals never get a Roman Numeral?

• Silver (Ag): Always +1

• Zinc (Zn): Always +2

• Cadmium (Cd): Always +2

Covalent compounds

• form when atoms of nonmetals share valence electrons to achieve stability

• nonmetal + nonmetal

covalent

double bond

triple bond

• occurs when atoms share two pairs of electrons

• occurs when atoms share three pairs of electrons

• forms when there are not enough electrons to complete octets

what kind of bonds have polarity?

covalent bonds

non polar molecules

• H2, Cl2, O2 —> nonpolar

• polarbonds can be nonpolar if they cancel each other out in symmetrical arrangement (CO2, CCl4)

• electrons shared equal

polar molecules

• one end of the molcule= more negatively charged

• polar bonds do not cancel out

• electrons shared unequally

• ex: HCl

How does an Ionic Bond differ from a Polar Covalent bond in terms of electrons?

• No sharing. One atom is so strong it completely steals the electron.

• Composition: Usually a Metal + Nonmetal.

Predicting bond type by electronegativity differences

???

electronegativity

the measure of an atom's ability to attract shared electrons in a chemical bond towards itself

most electronegative element

least electronegative element

F

Cs

ionic bonds

• strongest most attractive force

• solids at room temp

• high melting pt

dipole dipole attractions

• in covalent polar molecules

• have dipoles where positively charged end of dipole in one molecule is attracted to negatively charged end of the dipole in another molecule

hydrogen bonds

• hydrogen atoms bonded to F, O, N or a lone pair of F, O, N

dispersion forces

• weak attractions between nonpolar molecules

• caused by temporary dipoles

• make it possiuble for nonpolar molecules to form liquids

what are diatomic molecules and which elements are they?

• diatomic molecules exist in nature in twos

• hydrogen, nitrogen, flourine, chlorine, bromine, iodine, oxygen

• Have No Fear of Ice Cold BeeR

exceptions to the octet rule

• hydrogen fills octet with 2 ve

central atoms w 2 electron groups

linear, 180 degrees

CO2

central atoms w three electron groups + 0 lone pairs on central atom

trigonal planar 120

H2CO

central atom w 3 electron groups (one of which is a lone pairs on the central atom)

bent 120

SO2

central atoms w 4 electron groups

tetrahedral 109

central atoms w four electron groups (1 lp)

trigonal pyramidal 109

NH3

central atom w 4 electron groups (2 lp)

bent 109

H2O

electronegativty

the measure of an atom's ability to attract shared electrons in a chemical bond

electronegativity trends

• Across a Period (Left to Right): Electronegativity increases. (The atoms get better at pulling electrons).

• Down a Group (Top to Bottom): Electronegativity decreases. (The atoms get larger, and the nucleus is too far away to "pull" effectively).

• most= F, least Fr

VESPR - valence shell electron-pair repulsion (V SEPR) theory

• describe oreintation of electron groups around central atom

• states that electron groups are arranged as far apart as possible around central atom

• specific shape of molecule is determined by the number of atoms attached to central atom