Module 4: Matter

Atom

• smallest unit chemical element broken down into

what does an atom contain

nucleus and orbital shell

what is in the nucleus

protons and neutrons

what is in the orbital shells

electrons

charge of proton

positive

charge of neutron

0, no charge

charge of electron

negative

what is an atom mostly made of

• empty space

• 99.99999%

what is an atoms normal state?

• same number of electrons and protons

• make charges neutal

neutral atom?

• same protons and neutrons

ionization

• adding or removing electrons to make it charged

• makes atom more chmically reacive

element

atoms w same # protons

• chemically simplest substances → broken down using chemical methods

what do all atoms of the same element have

• same chemical properties

what are the chemical properties?

• reactivity w other chemicals

• toxicity

• coordination #

• flamabiltiy

• enthalpy of formation

• heat of combustion

• oxidation states

• chemical stability

• types of chemical bonds that will form

covalent bond

• sharing of electrons

• strongest

ionic bond

• transfer of electrons

compoud?

atoms of diff elements bound together chemically

example of a compoud?

pure barium sulfate powder (BaSO4)

Mixture?

• combination of 2 or more substances not chemically bound together —> will seperate over time

example of mixture?

• barium sulfate suspenstion

• BaSO4 and H2O never chemically combine

molecule?

2 or more atoms chemically bound together

• smallest unit of a compound

what is the smallest unit of a compound

molecule

what is smallest unit of an element

atom

what is the only way to break down a molecule

• chemically

1869: what did Mendeleev do?

• 1st periodic table

• ordered them by weights

• noted some could be grouped together by similar properties

1895 and 1896: what did Rontgen and Bequerel do

• atoms contain pos and neg charged particles

• effected by magnetism and can be energized

1910: what did rutherford do?

nucleus has pos charge and surrounded by cloud of neg charge

1913: what did Bohr do?

• orbital shells

• electrons could drop shells emmitting quantum of energy

orbital?

volume of space wth specfic shape

shapes of orbitals

S, P, D, F

S orbital

P orbital

D orbital

F orbital

where can electrons inhabit in the orbitla shape volumes?

anywhere

what are shells or orbits broken down into

various suborbitals

what does bohr model of atom show

• only the shells

• is sufficient to illustrate most concepts of radiogrpahy

what does “shell” model help remeber

electrons only exist at certain set energy levels

what is an atom mostly?

space

why do objects seem “solid”

because collective negative electrical repulsion between outermost shells of their atoms

what is a protons weight compared to an electron

2000 times

atomic mass unit (AMU)

• mass of a prton

• is a standard to which all other particles are compared

• electron = 1/2000th AMU

Atomic # (z)

• number of protons

• determics identity

atomic number symbol?

Z

• also called Z #

who was the neutron predicted by

Rutherford

what is a neutrons mass

• mass is slightly heavier than a proton

• equal to a proton and an electorn

why is a neutron neutral

because it’s equal to an electron + proton

how does a neutron decay

• by splitting into a proton and electron

• electronis lighter so it gets ejected at high speed forming beta radiation

periodic table cloumn name?

group

what does group represent on the period is table

• z# left to right

• each group having similar properites

row on a periodic table name

period

what does a period represent

repeats cycle of chemical properties