Objective 4.03 Objective 4.03: Explain how the Periodic Table is a model for: Classifying elements...
-
Upload
thomasina-kellie-newman -
Category
Documents
-
view
219 -
download
0
Transcript of Objective 4.03 Objective 4.03: Explain how the Periodic Table is a model for: Classifying elements...
Objective 4.03
Objective 4.03: Explain how the Periodic Table is a model for:• Classifying elements• Identifying the properties of elements
Mendeleev’s Periodic Table
• Mendeleev’s periodic table arranges elements according to the atomic mass
• Atomic mass is the number of protons and neutrons
• Elements with similar properties are found in the same column
• Periodic table—chart that organizes information about all of the known elements according to their properties
http://www.aip.org/history/curie/periodic.htm
Today’s Periodic Table
• 1913, Henry Moseley showed that atomic number was the most important feature because it is what is responsible for chemical properties – Electron configuration determines chemical
properties
• Today elements are in order of the atomic number
• Atomic number—number of protons in the nucleus of an atom
Today’s Periodic Table
Periodic Table
• Chemical family or group is the Vertical column on the periodic table– All have similar properties, numbered 1-18 and
from 1A to 8A, all have same number of valence electrons
– Groups 1-2(IA-IIA) and 13-18(IIIA-VIIIA) are the main groups
– Groups 3-12 are called transition elements– Elements on the left side of the periodic table are
metals, except hydrogen– Elements on the right side of the periodic table are
nonmetals
Today’s Periodic Table
Properties of Metal Properties of NonmetalsSolid at room temperature, except mercury, which is a liquid
Most are gases, except bromine, which is a liquid
Malleable(shaped) and ductile (drawn into wire)
Brittle in solid phase
Have luster (shiny) Normally dullHave high thermal and electrical conductivity
Are poor conductors of heat and electricity
Tend to lose electrons in chemical reactions
Tend to gain electrons in chemical reactions
Reactivity describes how likely an element is to form bonds with other elements
Group 1 and Hydrogen
• Hydrogen is found above Group 1 but doesn’t belong to any group
• Placed here because it only has one valence electron. It’s properties are different from the other groups.
Alkali Metals
• Group 1 (Alkali Metals) on periodic table– Most chemically active – One electron in the
outer shell– Easily combine with
nonmetals– Reactivity of the metal
decreases with increasing atomic number
Reac
tivity
incr
ease
s
Alkaline Earth Metals
• Group 2 (Alkaline Earth Metal) on the periodic table – Highly reactive but less
reactive than group 1– Reactivity of the metal
increases with increasing atomic number
Reac
tivity
incr
ease
s
Transition Metals
• Group 3 –12 (transition metals) on the periodic table– Generally hard solids
with high melting points – Often form colored ions
Metalloids
• Metalloids– Found along the zigzag
between the metals and nonmetals on the periodic table
– Have properties of both metals and nonmetals
http://www.gordonengland.co.uk/elements/metaloids.htm
Halogens
• Group 17 (Halogens) on the periodic table– Most reactive of the nonmetals– Reactivity in nonmetals
increases as atomic number decreases
– Fluorine (F) is the most reactive
– Halogens react with alkali metals to form salts
– Elements in this family are all states of matter• Fluorine(Fl) and Chlorine—
gases• Bromine (Br)—liquid • Iodine (I) and Astatine (At) are
solids at room temperature
Noble Gases
• Group 18 (Noble Gases) on periodic table– Least reactive of all
elements– Inert—unable to react
chemically
Periods
• Periods are the rows• Elements in the same
period have the same number of electron orbits(shells)
• Atoms are similar sizes
• Electronegativity (tendency to attract electrons) increases from left to righthttp://www.chem4kids.com/files/elem_pertable.html
Periodic Table
• http://www.periodictable.com/
• http://www.bbc.co.uk/schools/ks3bitesize/science/chemical_material_behaviour/particle_model/revise1.shtml