Chemistry Midterm

example of qualitative observation

black table

descriptions

example of quantitative observation

3″ pencil

quantity observation

theory
a set of hypothesis that gives an overall explanation of some part of nature 
law
generally observed behaviors summarized into a statement
atom
fundamental unit of which elements are composed
_________tells what happens and _________ is our attempt to explain why it happens

law

theory

the law of constant composition applies to________
compounds
the fundamental particle according to Dalton
atom
The 1st scientist to show that atoms emit tiny negative particles
JJ Thomson
the tiny negative particles  
electrons
which atomic particle determines the chemical behavior of an atom
nucleus
The scientist whose alpha-particle scattering experiment led him to conclude that the nucleus of an atom contains a dense center of positive charge 
Ernest Rutheford
positive particle
proton
what 2 scientist discovered the neutron
James Chadwick and Ernest Rutheford
atoms with same # of protons but different # of neutrons
isotopes
mass # =
protons + neutrons
the # of protons in the nucleus of an atom 
atomic #

non metal

alkali metal

alkali earth metal

noble gas

halogen

 

[image]
elements right next to stair step like in periodic table
metalloids
lanthanides and actinides are periods also called
rare earth metals
different form of a given element
isotopes
Isotopic symbol

The normal chemical symbol is used for the isotope with the addition of the atomic number (Z) at the lower left of the symbol and the atomic mass number (A) at the upper left as shown [image]X. 

who is given the credit for the developing the periodic table of elements
Mendeleev
naming binary compounds

1.  Write the name of the element represented by the first symbol in the formula.

2.  Write the name of the element represented by the second symbol in the formula, but change the ending of the element’s name to “ide”.

3.; Check a reference table to determine the number of positive oxidation numbers that the first element forms.; If it only forms one then you are done.

4.; If the first element shows more than one oxidation number, than use the stock system.; Determine the oxidation number that the first element is showing and write that roman numeral in-between the two elemental names.

Rules for Naming Acids that;Do Not Contain Oxygen;in the Anion:

  • Since all these acids have the same cation, H+, we don’t need to name the cation.
  • The acid name comes from the root name of the anion name.
  • The prefix hydro- and the suffix -ic are then added to the root name of the anion.

Rules for Naming Oxyacids (anion contains the element oxygen)

  • Since all these acids have the same cation, H+, we don’t need to name the cation.
  • The acid name comes from the root name of the oxyanion name or the central element of the oxyanion.
  • Suffixes are used based on the ending of the original name of the oxyanion. If the name of the polyatomic anion ended with;-ate, change it to;-ic;for the acid and if it ended with;-ite, change it to;-ous;in the acid.

Naming Polyatomic compounds

;The cation is written first in the name; the anion is written second in the name.

Rule 2.;When the formula unit contains;two or more;of the;samepolyatomic ion, that ion is written in parentheses with the subscript written outside the parentheses.

    Note: parentheses and a subscript are;not;used unless more than one of a polyatomic ion is present in the formula unit (e.g., the formula unit for calcium sulfate is “CaSO4” not “Ca(SO4)”).

Rule 3.;If the cation is a metal ion with a fixed charge, the name of the cation is the same as the (neutral) element from which it is derived (e.g., Na+;= “sodium”). If the cation is a metal ion with a variable charge, the charge on the cation is indicated using a Roman numeral, in parentheses, immediately following the name of the cation (e.g., Fe3+;= “iron(III)”).

Rule 4.;If the anion is a monatomic ion, the anion is named by adding the suffix;-ide;to the root of the element name (e.g., I;= “iodide”).

;electronegativity

the measure of the attraction of an atom for the electrons in chemical bond

—-increases

l                    

decreases                  

ionization energy

energy required to completely remove an electron from an atom or ion

—–decrease

l                     

increase                  

how to determine p/e/n in ions

p remains the same

n remains the same

e changes according to number

+ = subtract

– = add

pure substance
A sample of matter, either an element or a compound, that consists of only one component with definite physical and chemical properties and a definite composition. 

C and c 

physical and chemical properties

Physical properties are charecteristics of a pure substance that can be observed without changing it into another substance. Chemical properties are charecteristics of a pure substance that describes its ability to change into different substance. 

c and c 

physical and chemical change

A chemical property is a characteristic of a substance that is observed when it undergoes a chemical change. 

1) Physical properties are properties of an element or compound that can be observed without a chemical reaction of the substance. Density and electrical conductivity are examples of physical properties.

solids
Solids – Keep their shape
Definite mass ( will not change in size )
Definite volume ( will not change shape )
High melting point
Molecules vibrate slowly in place

liquids

 

Liquids – Take shape of container
Definite mass
Indefinite volume ( will change in shape under certain conditions )
Molecules vibrate rapidly and freely

gases

 

Gases – Take shape of container and fill completely
Indefinite mass and volume
Expand rapidly and evenly to fill container
When released in large area ( class room, outside, outer space, ) will fill entire area and become extremely scarce.
x

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