Structure of Matter Flashcards
Proton-
Symbol:
Location:
Charge:
Mass:
Symbol: p+
Location: Inside nucleus
Charge: Positive
Mass: 1 amu.
Neutron-
Symbol:
Location:
Charge:
Mass:
Symbol: n0
Location: inside nucleus
Charge: neutral
Mass: 1.00 amu.
Electron-
Symbol:
Location:
Charge:
Mass:
Symbol: e-
Location: orbiting nucleus
Charge: negative
Mass: ~1/2000
Atomic Number
The identity of an element or the number of protons
What is Atomic Mass?
The average mass of the nucleus of all the atoms of an element. #protons + #neutrons
Number of Electrons per shells? (1-7)
First Shell: 2 Second Shell: 8 Third Shell: 18 (Z< 21, then 8) Fourth Shell: 32 Fifth Shell: 32 Sixth Shell: 18 Seventh Shell: 8
How many valence electrons can there be?
Number of valence electrons can be between 1-8 in sequential order for Groups 1,2 and 13-18. (note: Groups 3-12 are more complicated and not included on the test).
True or False: Electron-Dot Diagram shows ONLY the number of valence electrons around the element symbol.
True
Calculating # of protons:
Protons = Atomic Number
Calculating # of Neutrons
# Neutrons = Atomic Mass (rounded) - Atomic Number. note: Atomic Mass=p + n
Calculating # of Electrons
For a NEUTRAL atom, #electrons = #protons.
Z is…
Atomic Number
A is…
Atomic Mass
Mass of nucleus:
of protons + # of neutrons
Periodic Table
The arrangement of elements in order of atomic number that shows elements grouped together with other elements of similar properties to form a repeated pattern.
What are the three categories of Elements?
- Metals
- Nonmetals
- Metalloids
What are some characteristics to help you classify METALS?
Good conductors heat/electricity. Malleable/Ductile. Shiny. Solid @ Room Temperature. Lose Electrons.
What is special about METALLOIDS?
They have properties of both metals and nonmetals.
What are some characteristics of NONMETALS
Poor conductors heat/electricity. Brittle. Dull. Gas @ Room Temperature. Gain Electrons.
What are groups?
The vertical columns where the number of valence electrons are the same, so the elements have similar properties.
Metal Groups:
Most reactive on the left (Groups 1 and 2), less reactive in the middle (Groups 3-12).
Nonmetal Groups:
Most reactive on the right (Group 17) less reactive in the middle (Groups 16-13).
What is special about group 18?
Group 18 is unreactive because the outermost shell is full.
Patterns
Many patterns are formed when elements are placed in groups on the Periodic Table.
History:
In the early 1800s, scientists believed that the 55 known elements could be organized in a useful way. In 1869, Dmiri Mendeleev arranged the elements in order of increasing atomic mass and noticed patterns started to form. Mendeleev left gaps in the table for elements that were not yet discovered. Henry Moseley changed Mendeleev’s table by placing the elements in order of increasing atomic number.
What are periods?
The horizontal rows where the number of valence electrons increases by 1, the atomic number increases by 1, and the Period Number equals the number of energy shells.
What are Groups?
The numbers at the top
Alkali Metals?
Group one except for Hydrogen
Very highly reactive, not found freely in nature, soft, low density metal (Li, Na, K float on water) low boiling point
Alkaline Earth Metals?
Group 2
Highly reactive, not found freely in nature, hard
Transition Metals?
Groups 3-12
Bridge between highly reactive and less reactive metals, malleable, can bond with inner electrons, very hard, high melting/boiling point
Rare Earth Metals
The ones at the bottom
Lanthanides - Soft, used for allloys, hard to distinguish
Actinides: unstable/radioactive, decay quickly, very high density
Poor Metals and Poor Nonmetals (Boron, Carbon, Nitrogen, Oxygen Groups)
13-16
Least reactive metals and nonmetals
Halogens
Group 17
Dangerous to humans, very highly reactive, bond with many elements
Noble Gases
Group 18
Unreactive (full outermost shell), very low boiling points, combine with very few elements only under certain conditions
