Understanding chemical reactions requires a grasp of various fundamental concepts. Atoms are represented by element symbols, and the number of atoms is indicated by subscripts. Coefficients in chemical equations help balance the reactions by multiplying the subscripts of the elements involved.
Counting atoms: - Symbol of elements represents 1 atom of that element. e.g: Ca = 1 carbon - Subscript is written on lower right hand and represents # of atoms in that element e.g:N sbs 2 = 2 nitrogen - Subscript outside brackets multiplies everything inside. e.g: Ba sbs 3 (po sbs 4)sbs 2 = 3 barium, 2 phosphorus, 8 atoms of oxygen - coefficient infront represents # of atoms for that symbol.
How to balance chemical equations: - multiplying and placing coefficient in front of each substance - coefficient can multiply all subscripts
Balancing Reactions: a balanced reaction has same number of atoms of each element on both sides.
Exothermic: energy is released into surroundings Exothermic: energy is absorbed through the surrounding.
Physical states of reactants and products: -Gas (g) -Liquid (l) -Solid (s) - (Aqueous)
Reactants turn into products A + B = C + D
Chemical equation describes chemical reaction using formulas and symbols
Unit 6: Chemical Reactions:
Diatomic molecules: form when 2 non metals of different EN bond together. -equal sharing of electrons - no pole of charge + and - - found in pairs 2 bonded together = *H2 O2 F2 Br2 I2 N2 Cl2
VSEPR stands for : Valence, Shell, Electron, Pair Repulsion. = explains shapes of molecules. Bonding and non- bonding electron pairs will be farthest apart from each other so they don't repel.
Lewis structures: how to draw lewis structures: - Count valence electrons for each element and add them. - Put the element that has least # of electrons in the center and draw bonds to connect it to other elements - keep adding electrons until all of the elements are happy, fill the octet!
Chemical Bonding 2:
Intramolecular forces: are strong forces that holds atoms together in a molecule.
Intermoleular forces: are weak forces that are found between molecules.
Delta Polarity: forms when 2 nonmetals of of different EN bond together. -Unequal sharing of electrons - results in poles on - and + charges
Non - Polar Covalent = 0 Polar Covalent = 0.1 - 2.1 2.1 and higher = Ionic
Calculating EN values: Use the EN value chart to find the difference between the EN of 2 elements. To find the difference subtract the least EN from the most EN H=2.1 , F=4.0 = 4.0 - 2.1 =1.9 = Polar covalent
Electronegativity: calculation how strongly an element pulls an electron towards its nucleus
Ionic bond: forms between ions. Electrostatic attraction holds ions together. ( Nonmetal + metal)
