ghsgt comprehensive review day 1 structure and properties of atoms
TRANSCRIPT
GHSGTComprehensive
Review
Day 1
Structure and Properties
of Atoms
Understanding of an Atom
What is the definition of an atom?
1.All matter is composed of extremely small particles called atoms
2. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, & other properties
ELEMENT2
ELEMENT2
ELEMENT 3
ELEMENT 3
ELEMENT 1
ELEMENT 1
ELEMENT4
ELEMENT4
Atomic TheoryAtomic Theory
3.Atoms cannot be subdivided, created, or destroyed
4.atoms of different elements combine in simple whole # ratios to form chem compds
5. in chemical rxns, atoms are combined, separated, or rearranged
++ ++
Atomic TheoryAtomic Theory
• All atoms consist of 2 regions that contain the subatomic particles–The nucleus–The electron cloud around the nucleus
• The nucleus is a very small region located near the center of the atom– In every atom the nucleus contains
• At least 1 proton (p+) which is positive• At least 1 neutron (no) which is neutral
Atomic StructureAtomic Structure
• The electron cloud is the region that surrounds the nucleus –This region contains 1 or more
electrons (e-), which are negatively charged subatomic particles
–The volume of the electron cloud is much larger than the nucleus
Atomic StructureAtomic Structure
electron e- -1 0 9.11x10-28
proton p+ +1 1 1.67x10-24
neutron n0 0 1 1.67x10-24
Structure of the AtomStructure of the Atom
Atomic StructureAtomic Structure
• With the exception of Hydrogen, every nucleus contains 2 kinds of particles protons and neutrons– they make up the mass of the atom
(Mass Number = Protons + Neutrons)• Proton has a charge equal to but
opposite of the charge of an elec.–Atoms are neutral because they
contain equal #’s of protons & electrons
Structure of the AtomStructure of the Atom
• The atoms of different elements differ in the # of protons in their nuclei and therefore in their positive charge–The # of protons the atom contains
determines the atom’s identity•Only Oxygen contains 8 protons•Only Fluorine contains 9 protons•Only Neon contains 10 protons
Counting AtomsCounting Atoms
• Basic Truth: All atoms contain the same basic parts, but atoms of different elements have different numbers of protons.–The PT lists atoms in consecutive
order by their Atomic Number (Z) –The atomic number is directly
related to the number of protons in the nucleus of each atom of that element
Counting AtomsCounting Atoms
• The atomic number is found above the elemental symbol on the PT and it defines the type of element–Atomic #47 can only be Ag and it
also can only have 47 protons in each nucleus
–Because atoms are neutral, we know from the atomic number the atom must also contain 47 electrons.
Counting AtomsCounting Atoms
• The total number of protons & neutrons determines the mass of the atom–Called the Mass Number–A Carbon atom, has 6 protons and 6
neutrons, so its mass number is 12• If you know the atomic number &
mass number of an atom of any element, you can determine the atom’s composition
ATOMS OF THE 1ST TEN ATOMS
NAMESYMBO
LATOMIC
# p+ n0 MASS # e-
Hydrogen H 1 1 0 1 1Helium He 2 2 2 4 2Lithium Li 3 3 4 7 3
Beryllium Be 4 4 5 9 4Boron B 5 5 6 11 5
Carbon C 6 6 6 12 6Nitrogen N 7 7 7 14 7Oxygen O 8 8 8 16 8Fluorine F 9 9 10 19 9
Neon Ne 10 10 10 20 10
Counting AtomsCounting Atoms
• Every Cl atom has 17 protons, w/o exception, but not every Cl atom has 18 neutrons.–Atoms with the same # of protons
but contain different #s of neutrons are called isotopes.•Since isotopes of an element have different #s of neutrons they have different masses
Counting AtomsCounting Atoms
• Isotopes are chemically alike because they have identical numbers of protons and electrons–It’s the electrons and protons that
are responsible for chemical behavior
• Isotopes can be noted using hyphen notation (Cl-35 vs Cl-37)–elemental symbol hyphen mass
number
Isotope: one of two or more atoms having the same number of protons but different numbers of neutrons
or Na-23 or Na-24
PracticePractice
Name SymbAtomi
c #Mass #
# p+ # e- # n0
Isotopic
Symbol
Strontium
W
82
70 As7433