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What is Daltons Atomic Theory

All matter is made up of atoms
Atoms of the same element are identical however difference to atoms from other element
Compounds - combo of 2 or more different elements
In chem reactions- atoms are combined, separated or rearranged
Atoms are never created or destroyed


Molecules what are they

Electrically neutral group of two or more atoms.
Can be of the same or different non metal elements- held together by covalent bonds
O2 - 2 atoms of oxygen
H2 - 2 atoms of hydrogen
H2O - 2 hydrogen and 1 oxy
CO2 - 1 carbon and 2 oxygen


What value is noted as subscript?

Atoms/elements present in numbers greater than 1


Atoms what are they

Have a single nucleus and its electron cloud
Electrons in the outer shell are involved in the reaction of atoms
The outermost shell of an atom in its uncombined state – Valence (electrons) shell involved in reactions
Every element within a group has the same number of valence electrons Corresponds to the group number 2, 8, 8, 2


Ions what are they

An atom containing an equal number of protons and electrons is electrically neutral
Ions are atoms that have acquired a net positive or negative charge by loosing or gaining valence electrons
Ions are expressed as the symbol/element with a superscript, showing the magnitude and sign of the charge eg NA+, CA2+



Loss of electron -- convert the atom to a positive ion
Number of protons greater than the number of electrons



Gain of electron ------ convert the atom to a negative ion



An atom gain or loose electrons to create a stable outer valence shell ( ionization)
When the electron shell is filled with electrons then the element is stable and unreactive


Bohr Model

Shows all the electrons in the shells


Positively charged ion

Lose electrons when 1, 2 or 3 electrons are in the outer valence shell usually metals. Note these electrons also denote electron groups


Negatively charged ion

Gain electrons when 6 or 7 electrons are in the outer valence shell usually nonmetals


ionic bond

An ionic bond is a chemical bond that involves a metal and a nonmetal ion
Atoms either losing or gaining negatively charged electrons, reacting to form ions
Positive ions (metals) are attracted to negative ions (nonmetals)
In naming simple ionic compounds, the metal (cation) is always first, the nonmetal (anion) second


Lewis Dot Structure

Similar to the Atomic Structure – except only the valence shell is shown
Indicated by dots
Sometimes referred to as the electron dot structure


Characteristics of plasticware

Cheaper and more durable (unbreakable). lightweight and impact- and corrosion-resistant
Disadvantage – some leaching of surface bound constituents into solutions and evaporation through plastic


Characteristics of Glassware

Frequently preferred for analytical work because of it’s chemical stability and clarity
Special types of glass have been devised for special use
flint glass/soda lime, borosilicate glass, or quartz/silica glass



used for graduated cylinders



petri dish, test tubes



milky or opaque appearance and are heat resistant


Flint glass (soda lime):

Inexpensive, low resistance to heat and chemicals. Used to make disposable test tubes


Borosilicate glass

Nonreactive with most chemicals, high thermal (heat) resistance glassware
Used for most lab glassware, Pyrex and Kimax


Quartz/Silica glass:

Very expensive, contains only silica quartz with excellent optical qualities
Used for high precision work – spectrophotometry cuvettes, microscope lens


Volumetric pipette

Used for critical/accurate measurements
Calibrated to deliver “TD” a single volume
Has a bulged out portion (bulb) in the middle


Serological/Graduated pipette

Calibration marks to the tip
Etched ring around the top – last drop must be blown out
Mainly used for preparing serial dilutions
Transfer total capacity or partial volumes


Mohr pipette

Not calibrated to the tip
Do not drain beyond last calibration marking