ch. 8- Atoms Flashcards
Elements
Matter that is composed of one type of atom
Scientific shorthand
A letter or pair of letters called a chemical symbol
Compounds
Form when two or more elements combine chemically
Molecule
Smallest unit of any compound
Atom
Smallest piece of matter that still has the properties of the element
Nucleus
Located in the center of the atom
-made of protons and neutrons
Protons
+1 charge
Neutrons
Neutral charge/no charge
Electrons
-1 charge
Electron cloud
Model showing electrons traveling in specific energy levels around a nucleus
Valence electrons
Electrons in outer shell
- highest energy
- involved in bonding
Quarks
Smaller particles that make up protons/ neutrons
-only 6 known to exist
Atomic mass
Protons + neutrons
-also called mass #
Atomic #
# of protons in an atom - every elements has a different atomic #
Isotopes
Atoms of the same element that have different #’s of neutrons
Average Atomic Mass
Average mass of all isotopes of that element
First periodic table:
- made by Dmitri Mendeleev i the late 1800’s
- based on atomic mass
Periodic table used today
- made by Henry G. J. Mosley in 1913
- arranged by atomic #
Groups
- vertical columns of elements with similar properties
- # 1-18
- elements in same group have same # of VE
Periods
- horizontal rows of elements that contain increasing #’s or protons/ electrons
- numbered 1-7
- each row ends when an outer energy level is filled
Metals location
-located to the left of the stairstep
Metals properties
- react by losing VE
- good conductors of heat/ electricity
- solid at room temp. except mercury (Hg)
Reactivity depends on what?
- how easily its atoms loses VE
- reactivity decreases from left to right
What are the 3 metal types?
Alkali metals, alkaline earth metals, and transition metals
Alkali metals
- group 1 elements
- most reactive
- don’t occur alone naturally
Alkaline earth metals
- group 2 elements
- shiny, ductile, malleable
- combine readily with other elements
- still very reactive
Transition metals
- group 3-12 elements
- most familiar metals because they occur naturally uncombined
Inner transition metals
- lanthanides series with atomic #’s 57-71
- actinide series with atomic #’s 89-103
Nonmetals
- become stable when they gain or share enough electrons to have 8 VE
- usually combine with metals by gaining electrons
- can combine with other nonmetals and metalloids by sharing electrons
Halogens
- group 17 elements
- contain 7 VE
- react easily with other elements
Noble gases
- group 18 elements
- exist as isolated atoms
- are stable bc outer energy level is filled
Metalloids location
-make up stairstep
Metalloids properties
- have metallic and non-metallic properties
- a part of the mixed groups
Hydrogen
-considered a nonmetal
Mixed groups
Contain metals, nonmetals, and metalloids
-group 13-17
