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specific heat
Chapter 7: Energy
Chapter 9: Bonding
chemical reactions
SI unit = Joules
a representation of the valence electrons of an atom that uses dots around the symbol of the element.
it does not matter on which sides of the symbol the electron dots are positioned
Lewis Dot Structures
number of dots equals the number of valence electrons in the atom
endothermic vs exothermic
octet rule: atoms like to have eight electrons in their valence shell
These dots are arranged to the right and left and above and below the symbol, with no more than two dots on a side
Ionic Bond:
the number of electrons lost must equal the number of electrons gained.
caused by electrons transferring from one atom to another.
Covalent Bond:
the attraction between oppositely charged ions
Law of Conservation of Energy
the electrons are shared between two atoms.
Q = Cm T
= Tf - Ti
mass
temperature change
specific heat
heat energy
Endothermic
=
positive delta-H
total energy of an isolated system does not increase or decrease
gains/absorbs energy
cools surroundings
Hess' Law
by algebraically combining chemical equations, we can generate new chemical equations that may not be feasible to perform.
products are higher on vertical energy scale than reactants
Exothermic
When chemical equations are combined algebraically, their enthalpies can be combined in exactly the same way.
negative delta-H
loses/gives off energy
1.
If a chemical reaction is reversed, the sign on delta-H is changed.
If a multiple of a chemical reaction is taken, the same multiple of the delta-H is taken as well.
2.
heats surroundings
products are lower on vertical energy scale than reactants
Chemistry