Post on 11-May-2017
Science is a systematic or organized body of knowledge obtained through observation and experimentation.
Chemistry is a branch of science that deals with the study of matter(properties, structure, composition, changes and principles/laws that govern changes in matter).
Measurement SI Units commonly used
Length Meter (m) Meter (m)
Mass Kilogram (kg) Gram (g)
Volume Cubic meter(m3) Liter (l) , ml.
Amount of Substance
Mole(mol) Mole(mol)
Temperature Kelvin (K) Celsius( ◦ C)
1ml=1cm3 (or cc.); 1Liter = 1000 ml.=1000 cm3 (or cc.) = 1dm3
* 273 K = 0 ◦ C = 32◦ F
Prefix Symbol Meaning Tera T 1012 Giga G 109 Mega M 106
Kilo k 103
Deci d 10-1 or 1/10
Centi c 10-2 or 1/100
Milli m 10-3 or 1/1000
Micro u 10-6 1/1000,000
Nano n 10-9
Pico p 10-12
Temperature:
◦ F = 9 ◦ C + 32; 5
◦ C = 5 ( ◦ F - 32) 9
K= 273 + ◦ C
Density: D(g/ml) = Mass/Volume ; D (g/L ) = M / V
for solids and liquids for gas
Accuracy tells how close a measurement is to the true value.
Precision tells how close two or more measurements agree with one another.
Accuracy – how close a measurement is to the true valuePrecision – how close a set of measurements are to each other
Accurate &Precise Precise but
not accuratenot precise &
not accurate
Properties of Matter
Properties –qualities or characteristics by which a given substance is identified.
Physical Properties qualities that can be observed with the senses,without changing the composition of the susbstance. Ex. colors, shapes, size
Chemical Properties
qualities that can be observed after alteration of composition of the substance
Ex: iron rust, hydrogen is flammable
Extrinsic or Extensive Properties• are properties that depend on the amount of the
substance in a sample • Ex: volume, length, mass
Intrinsic or Intensive Properties do not depend on the amount of substance ex.
density, boiling pt. melting pt
Changes of Matter
Physical Change change in size, shape, physical state, no change in nature or compositon.Ex: freezing of water, pulverizing salt distillation of wine
Chemical Change • change in the compositon of the
substance • a new substance is formed.• ex iron nail (Fe) → rust (Fe2O3) • charcoal (C) Δ CO2
• Fermentation of fruit juice
Molecules = aggregate of two or more atoms held by a chemical bond.
I. Diatomic molecule is composed of two atoms.
a. with two similar atoms (element) ex: H2, N2, Cl2, F2
b. with two different atoms (compound) ex. HI, HF, CO, HCl
2. Polyatomic molecule is composed of three or more atoms.
a. with three similar atoms ex: O3 b. with three different atoms ex: HCN,
NH3, CaCO3, C6H12O6
Ion = an atom or a group of atoms that has a positive(+) or negative(-) charge.
a. Cations are positively charged ions ( formed when there is a loss of one or more
electrons) ex: Na + , Ca +2, Al+3
Na◦atom 11p +11 e- = O; Na+cation11p + 0 e- = +1
b. Anions are negatively charged ions (formed when there is a gain of one or more
electrons) ex: Cl- , O -2
Cl◦ atom 17p + 17 e- = o; Cl- anion17p + 18e- = -1
Mass number (A) = the total number of protons + number of neutrons
Atomic number (Z) = the number of protons in the nucleus of an atom.
A X
Z
12
6 C17
9 Cl
Isotopes of Hydrogen
2 1 H
1
1 H3
1 H
Protons = _
Neutrons=_
Protons = _
Neutrons=_Protons = _
Neutrons =_
Isotopes of Hydrogen
2 1 H
1
1 H3
1 H
Protons = 1
Neutrons= 0
Protons =1
Neutrons= 1Protons = 1
Neutrons = 2
Isotopes of Uranium
235 92 U
234
92 U238
92 U
Protons = 92
Neutrons=
Protons =92
Neutrons=Protons = 92
Neutrons =
Isotopes of Carbon and % Abundance
13 6C
12
6 C
Protons = 6
Neutrons= 6 Protons = 6
Neutrons= 7
% abundance =98.89%% Abundance = 1.11%
Computations:12 x 0.9889 =11.866813 x 0.0111 = 0.1443 12.0111 atomic weight 12. atomic mass (mass no.)Mass no.- the whole no. nearest to the exact
atomic weight
Atomic Structure : Atom- basic unit of an element that can enter into a chemical reaction, retains the identity of element
Electron (discovered by Joseph John Thomson) is negatively charge(-) particle
Neutron (discovered by James Chadwick) is electrically neutral particle.
Proton and atomic nucleus (by Ernest Rutherford) positively charged(+) particle.
Chemical formula represents the composition of one molecule or ionic compound in terms of chemical symbols. a. Molecular formula shows the actual number of atoms of elements in a molecule.
ex: C6H 12O6 ( sucrose), C6H6 (benzene ) ,C2H2 (acetylene) .
b.Empirical formula gives the simplest whole number ratio of atoms of elements in a molecule ex: C H2 O ( sucrose), C H (benzene ) , C H (acetylene)
c.Lewis formula shows the valence electrons of atoms of elements in a molecule. .. .. ..
ex: H: O : O: H (hydrogen peroxide) H: O :H (water) .. .. .. d. Structural formula shows the binding of atoms of elements in a molecule.
ex: H-O –O -H (hydrogen peroxide) H- O -H (water)
Electronic Structure of Atoms
Aufbau PrincipleAtomic orbitalsElectronic configurationOctet RuleHund’s Rule
Reduction Oxidation Reaction
Molecular Equation (Valence Change Method)NaNO2+ K2Cr2O7 + H2SO4 = NaNO3 +K2SO4 + Cr2 (SO4) 3+ H2O
Ionic Equation (Valence Change Method) NO2 + Cr2O7 + H + = NO3 -1 + Cr + H2O
Half Reaction or Ion-electron method NO2
-1 = NO3 -1
Cr2O7 -2 = Cr+3
+3
-2 -1
Redox
Balance the eq. using Valence change or Ion electron method . Answer #1-10MnO4
-1 + ClO2
-1 +H2O = MnO2 + ClO4 -1 + OH-
___1. Oxidation no. of Mn in MnO4 -1
___2. Oxidation no. of Cl in ClO 4 -1
___3. electron lost/mole ___9. coefficient of ClO2-1
___4. electron gained/mole ___10. coefficient of MnO2
___5 Identify the OA___6. Which is the RA?___7. Which is the reduction product?___8. Which is the oxidation product?
Concentration Units
Molarity – moles of solute per liter of solutionM= moles solute moles = g solute liter of solution molar mass g solute M = molar mass liter solution
Normality – no of equivalents of solute per liter of solution
N = equivalents of solute liter of solution
g soluteN = eq wt liter of solution
molality - moles of solute per kg solvent g solute m = molar mass kg solvent
% by mass = mass solute X 100 mass of solution
Mole fraction solute (X2) = mole solute mole solution
Mole fraction solvent (X1) = mole solvent mole solution
Concentration Units
1.Calculate the % by mass of the solute in: a. 5.50 g NaBr in 78.2 g solutionb. 31.0 g KCl in 152.0 g water 2.A solution is prepared by mixing 62.5 ml C6H6 (MW 78g/mol) with 80.3 ml toluene(MW 92.0g/mol) density C6H6 0.867 g/ml
density C7H8 0.87 g/ml.