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					Atoms and Elements Melaku Michael (ethiomelaku2)

Matter
Defined as anything that takes up space and has mass  Structure of matter refers to its composition – what matter is made of – AND how matter is organized…  Properties of matter describe the characteristics and behavior of matter, including changes that matter undergoes  Phase changes….


Phase Changes
phases of matter: solid ---- liquid ---- gas  See board diagram for phase changes…
3

ATOMS
are the basic building blocks of matter that make up everyday objects.  A desk, the air, even you are made up of atoms!
Atoms

The atom

Sections of an Atom
 Nucleus

– protons and neutrons are found here – electrons are found here

 Orbitals

Parts of the Atom
Electron = negative particle circling the nucleus  Proton = positive particle found in the nucleus  Neutron = neutral particle found in the nucleus

e le c tr o n n e u tr o n

p r o to n

ELEMENTS
that cannot be decomposed or broken into more elementary substances by ordinary chemical means.  More than 100 chemical elements are known to exist in the universe, although several of these have not been found in nature, and can only be produced artificially
 substances

Elements
90 occur naturally; the rest are synthetic or radioactive

Atomic Number
number of protons in the nucleus of an atom defines what element it is.  For example carbon atoms have six protons, hydrogen atoms have one, and oxygen atoms have eight.  The number of protons in an atom also determines the chemical behavior of the element.
 The

Atomic Mass
 The

number of protons AND neutrons in the nucleus of an atom

Atoms -- isotopes
Atoms with the same number of protons but a different number of neutrons are called isotopes (Ex. Carbon can exist as C12, C-13, C-14)  Some radioactive isotopes are unstable and tend to decay spontaneously giving off particles (neutrons) and energy. Also, this decay into more stable atoms occurs AT A PREDICTABLE RATE.


-these characteristics make isotopes good to use for radioactive dating, for use as tracers to follow the path of an atom in a series of reactions and for use in diagnosing disease.

Element Name and Symbol


Atomic Symbol: The atomic symbol is one or two letters chosen to represent an element ("H" for "hydrogen," etc.). Memorize the symbols/ names/atomic number of the following: S C He H Mg Na K Ca Fe Ni Cu Zn Ag Au Sn Pb Al N O P I Li Ba Cr Mn Co Cs Hg Si Cl Br F Ne Ar Rn

 

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    

We’re more than CHNOPS
Look at Table 6.1

Elements: ~25 elements are essential to life

What are trace elements? Found in the body in very small amounts, yet play vital roles!

Elements & Compounds


Elements
– All atoms are the same – Represented by chemical SYMBOLS



Compounds
– Combination of different amounts of different atoms – Represented by chemical FORMULAS

Compounds
 COMPOUNDS:

– A substance made of more than one element
 Example:

H2O = ?

– NOTE: the subscripts tell how many atoms of each element you have

– QUESTION:
 How

many ELEMENTS are represented by the water formula?
–2

 How

many ATOMS are represented by the water formula?
–3

 USE  KF

APPENDIX D – The Periodic Table

How many atoms? Try These…

– Potassium = __; Fluorine = __
 NaBr

– Sodium = __; Bromine = __
 H3PO4

– ???????? = __; ??????? = __; ?????? = __ – ?????? = __; ?????? = __; ?????? = __

 CuSO4

 Pb(NO3)2

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

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

KF – Potassium = 1; Fluorine = 1 NaBr – Sodium = 1; Bromine = 1 H3PO4 – Hydrogen = 3 – Phosphorus = 1 – Oxygen= 4 CuSO4 – Copper = 1 – Sulfur = 1 – Oxygen = 4 Pb(NO3)2 – Lead = 1 – Nitrogen = 2 – Oxygen = 6

How many atoms? Try These…


				
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posted:7/28/2009
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