Chem Presentation 1a
Last Modified: 2016-03-08
-All matter is made up of elements
-There are 92 naturally occiring elements.
-Elements are made of atoms.
-Each element has a symbol, made of letters from its name.
-Atoms of the same element share similar chemical properties
-Atoms are made up of sunbatomic particles.
It is calculated when measuring atomic mass, and has about the same weight as a proton.
All atoms of an element have the same atomic number.
Atomic mass measured in amu.
Mass number - Atomic number = number of neutrons.
Number of neutrons can vary in an element, but number of protons is constant.
Same number of protons, different number of neutrons. Naturally, elements occur as mixed isotopes. Different isotopes of the same element react chemically in the same way.
Some isotopes are radioactive. The nucleus decays, giving off particles and energy. The atom is transformed into a different atom.
An orbital is the 3D space ewhere and electron si found 90% of the time.
Holds a maximum of two electrons.
Three dumbbell-shaped orbitals each oriented at right angles to the other two (2px, 2py, 2pz orbitals).
Contain additional orbitals with more complex shapes
An atom with an incomplete valence shell is chemically reactive (tends to form chemical bonds until it has eight electrons to fill the valence shell).
Atoms with the same number of valence electrons show similar chemical behavior.
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