Names and SymbolsElements get their names in
different waysEach element has its own unique
symbolCapital letter indicates a new
element
Each Element is Made of A different Atom
John Dalton (Atomic Theory) said that each element is made of tiny particles called “atoms”
All of the atoms of a particular element are IDENTICAL but are different from atoms of other elements
Structure of an AtomSubatomic Particles found in the
atomName Charge Location Relative Mass
Proton positive Inside nucleus
2000
Electron negative Outside nucleus-orbit the nucleus
1 Way smaller than protons or neutrons
Neutron No charge Inside nucleus
2000
Nucleus of An AtomPositively charged nucleusContains neutrons and protons
Neutrons have no charge so overall charge for nucleus is positive
Atomic NumberThe IDENTITY of an atoms is
determined by the number of protons in the nucleus
Atomic Number- the number of protons in the nucleus
Atomic Number Examples
(page 28)
Atomic Number
Atomic Mass
Atomic number equals the number of protons or electrons
Atomic mass equals the number of neutrons + protons.
Atom Model Rubric- Due Wed 9/7Present to class- big grade !
Atom correctly modeledCorrect number of subatomic particlesCorrect location of subatomic particles Includes Key Items used to demonstrate creativity
(not just colored on the page)Atom square includes atomic mass,
number and symbolCorrect energy levels and electrons in
each
Tonight’s HW
Finish rest of page 34 and 35Use your periodic table to find out if the element is a solid, liquid or gas !
We’ll grade and check it tomorrow
Periodic TableDmitri Mendeleev- 1869Shows a periodic or repeating pattern of properties of the elements
Gaps- new elements discovered would complete the chart
Periodic table organizes atoms of the elements by properties and
atomic number Elements arranged by atomic number (number of protons)
Each square gives specific information about the atoms of an element
1. Number at top of the square, # of protons in the nucleus of that atom
2. Chemical Symbol- abbreviation for element’s name; contains one or two letters
Reading the Periodic Table
Some elements that have not been named are given a temporary 3 letter symbol
Name of the element is written below the symbol
The number below the symbol tells the average atomic mass of all the elements
Reading the Periodic Table
The color of the element’s symbol tells the physical state at room temperature.
White letters like H (hydrogen) indicate a gas
Blue letters indicate a liquidBlack letters indicate a solid
Reading the Periodic TableBackground colors of the square indicates whether the element is a metal, non-metal or metalloid.
Group Each column (top to bottom) is
called a group. Elements in a group share similar
chemical and physical properties Groups are read from top to
bottom The groups are labeled at the top of
the column Group are also called “FAMILIES”
Periodic Table has distinct regions
Three main regionsMetals on the leftNonmetals on the right (except hydrogen)
Metalloid between
Reactivity The element’s location on the table tells
us how reactive an element is
Reactive- how likely an element is to undergo a chemical change
Atoms in groups 1 and 17 are the
most reactive Elements in group 18 are the least
reactive
Bohr Model- Where electrons are found
Energy Superhighway Can hold 18 electrons
Energy Freeway Can hold 8 electrons
Energy Street Can hold 2 electrons
MetalsMost elements are metalsMetals conduct electricity and heat well and have a shiny appearance
Can be shaped easily by pounding, bending, or being drawn into a long wire
Reactive Metals
Group 1Alkali metalsEx: Sodium and Potassium
Group 2Alkali earth metalsLess reactive
Isotopes
Atoms of certain elements ALWAYS have the same number of protons, may not always have the same number of NEUTRONS.
Not all atoms of an element have the same MASS NUMBER
Ex: Chlorine- some have 17 protons and 18 neutrons, other chlorine atoms have 20 neutrons