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Warm Up 9/24/2013 - Identify the name and charge of the 3 subatomic particles. - How is atomic mass calculated? - How is atomic number calculated? For the isotope, Thorium-234: - What is the mass? What is the atomic number? How is Thorium-234 different from the other Thorium isotopes?.
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Warm Up 9/24/2013 - Identify the name and charge of the 3 subatomic particles. - How is atomic mass calculated? - How is atomic number calculated? For the isotope, Thorium-234: - What is the mass? • What is the atomic number? • How is Thorium-234 different from the other Thorium isotopes?
Warm Up 9/24/2013 - Identify the name and charge of the 3 subatomic particles. Proton +1, electron -1, neutron 0 - How is atomic mass calculated? Protons + neutrons - How is atomic number calculated? Protons For the isotope, Thorium-234: - What is the mass? 234 • What is the atomic number? 90 • How is Thorium-234 different from the other Thorium isotopes? Number of neutrons
Dmitri Mendeleeve • Organized the elements according to similarities in their properties • Henry Moseley • Determined atomic number of the atoms • Arranged the elements in order of atomic number
The Modern Periodic Table • Periods: horizontal rows • Groups: Vertical columns
Periodic Law • When the elements are arranged in order of increasing atomic number, there is a repetition of their physical and chemical properties. • Elements with similar properties end up in the same column on the periodic table.
Representative Elements Alkaline Earth Metals
Representative elements are divided into 3 classes: • Metals: conduct electricity well, have luster • Nonmetals: poor conductors of electricity, lack luster, brittle if solids • Metalloids (semi-metals): properties in between metals and non-metals
Metals • Alkali Metals: Group 1A • Alkaline Earth Metals : Group 2A • Transition Metals: Group 1-8B • Inner Transition Metals (rare earth metals) • Lanthanide Series • Actinide Series
Nonmetals • Halogens: Group 7A • Noble Gasses: Group 0 (also called Group 18) • Also called inert gasses • Do NOT participate in chemical reactions • Outer electron shell is full
The elements of a group have similarities in physical and chemical properties Electrons play an important role in determining the physical and chemical properties of elements.
Valence Electrons: electrons in the outermost energy level of an atom’s electron orbital • The number of valence electrons is related to group number. • To find the number of valence electrons for a representative element, look at it’s group number • Example: all elements in group 1A have one valence electron!
Journal • How can the number of valence electrons be identified? • How many valence electrons does Carbon contain?
Classifying elements by electron configuration • Lewis Dot Diagrams show the electrons found in the outermost energy level (the valence electrons) • Written using the elements symbol with dots representing the electrons. • Example: H He C
Journal • Draw the Lewis dot diagram for: Na Ca S Ne
Behavior of elements • Elements strive to have a full octet (8 valence electrons) • The reactions and characteristic bonding properties of elements are due to their interactions and “need” to complete their valence electron shell. We will study the characteristic reactions and behavior in the next couple of weeks!!!