Download Scientific Method - Virtual Medical Academy

Scientific Method:-#
#
#
#
Observations :- facts
natural law.
model :- 1- Predictions. 2-hypothesis.
theory:- experiments to test the theory.
Chemistry:-The study of matter and the changes it can undergo
MATTER:-Matter is any thing occupies space and has a mass.
Matter------> has mass , mass to weight , occupies space.
There are things you can see.. "e.x: water, tree, food".
And there are things you can't see.. " air, gas in gas cylinders".
Properties of Matter:-*Extensive Property-depends on specific sample
under investigation .
examples:
mass and volume
* Intensive Property
identical in all samples of
the substance.
examples:
color, density, melting point, etc.
1/ Physical Property
The characteristics of a substance that can be observed without changing the substance.
* Mass (EXTENSIVE property).
* Volume (EXTENSIVE property).
* Size.
* Shape.
* Density (INTENSIVE property).
* Freezing and Boiling Points.
* Odor.
* Colour.
Extensive property: depend on the quantity of
Substance.
Intensive property: does not depend on
the quantity of substance . >>
density = mass/ volume.
Temperature Relationships:-C = 100/180 * (F - 32)
F = (180/100)*C + 32
K = C + 273.15
- 40o F = - 40o C
2/ Chemical Properties
The characteristics of a substance that can be observed with changing the substance.
Burning>> CH4 + O2
Combination>> 2H2 + O2
Decomposition>> 2H2O
CO2 + 2H2
2H2
O2 + 2H2
REPLACEMENT REACTION:--
Substance & Mixture:-SUBSTANCE:
Is a form of matter which has a definite composition and distinct properties.
Mixture:
A combination of two or more substances in which the substances retain their distinct properties.
TYPES OF MIXTURES:-HOMOGENEOUS:
The composition is uniform (WATER + SALT)
HETEROGENEOUS:
The composition is not uniform (WATER + SAND)
Separation of Mixtures:-* Filtration .
* distillation.
* chromatography.
Filtration>>* separate solids by differences in melting points.
* separate solids by differences in solubility (fractional crystallization).
* mechanical separation.
Distillation>> *separation by differences in boiling point(fractional distillation).
* fractionating column - part of apparatus where separation occurs.
Chromatography >> * liquid-column
* paper
* thin-layer (TLC)
* gas
* HPLC
* electrophoresis (DNA mapping)
Pure Substances:-- Elements & Compounds
Elements:--
* Pure substances that cannot be separated into different substances by ordinary
processes.
* Are the building blocks of matter.
Examples:>>> carbon , calcium , gold.
Symbols from Latin Names
Latin name
Copper
Gold
Lead
Mercury
Potassium
Silver
Sodium
Tin
Symbol
Cu
Au
Pb
Hg
K
Ag
Na
Sn
Element
cuprum
aurum
plumbum
hydrargyrum
kalium
argentums
natrium
stannum
Compounds:-- * A substance that composed of atoms of two or more elements chemically united in
fixed proportions.
* Are separated only by chemical means
Examples:>>> carbon tetrachloride CCl4
Sodium chloride NaCL
calcium carbonate CaCO3
STATES OF MATTER:-- There are THREE states of matter>> solid , liquid , gas .
Physical States :-Solid >> fixed volume & shap.
Liquid >>- fixed volume.
- shape of container, horizontal top surface.
Gas>> takes shape and volume of container.
liquid crystal>> some characteristics of solid and some of liquid states.
Metals and Nonmetals:-Metals
* Located to the left of the heavy line.
* Shiny, ductile.
* Good conductors of heat and electricity.
Nonmetals
*Located to the right of the heavy line.
* Dull and brittle.
* Poor conductors.
----------------------------------------------------------
Atomic Theory
* Atoms are building blocks of elements.
* Similar atoms in each element.
* Different from atoms of other elements.
* Two or more different atoms bond in simple ratios to form compounds.
Subatomic Particles:-Particle
Symbol
Electron
Proton
Neutron
ep+
n
Charge
-1
+1
0
Location of Subatomic Particles:-10 cm
electrons
protons
neutrons
nucleus
10 cm
Atomic Number:-- Counts the number of Protons in an atom.
Atomic Number on the
Periodic Table
Atomic Number
Symbol
11
Na
All atoms of an element have
the same number of protons
11 protons
Sodium
11
Na
Learning Check
State the number of protons for atoms of each of the following:
A. Nitrogen ---->
1) 7 protons 2) 14 protons 3) 5 protons
B. Sulfur ---- >
1) 16 protons 2) 6 protons
3) 32 protons
C. Barium ---- >
1) 137 protons 2) 81 protons 3) 56 protons
Mass Number:-- Counts the number of protons and neutrons in an atom.
(A) mass number
(Z)
23
Na
atomic number
11
Number of Electrons:>>>
* An atom is neutral.
* The net charge is zero.
* Number of protons = Number of electrons.
* Atomic number = Number of electrons.
* Mass number = Number of protons + Number of neutrons.
Examples>>
65
Zn
30
31
16
P
O
8
15
30 p+
35 n
30 e-
15 p+
16 n
15 e-
8 p+
8n
8 e-
Isotopes:-* Atoms with the same number of protons, but different numbers of neutrons.
* Atoms of the same element (same atomic number) with different mass numbers.
Example>>>
Isotopes of chlorine
35
37
Cl
17
Cl
17
Learning Check
1/Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons,
neutrons, and electrons in each of these carbon atoms.
12
13
C
C
6
#p ___6____
#n __6_____
#e __6_____
14
C
6
6
____6___
___7____
____6___
_____6__
____8___
____6___
----------------------------------
2/ An atom of zinc has a mass number of 65.
(A): Number of protons in the zinc atom >>
1) 65
2) 35
3) 30
(B): Number of neutrons in the zinc atom >>
1) 65
2) 35
3) 30
(C): What is the mass number of a zinc isotope
with 37 neutrons?
1) 67
2) 65
3) 37
------------------------------------
3/ Write the atomic symbols for atoms with the following:
A. 8 p+, 8 n, 8 eB. 17p+, 20n, 17e-
_________________
_________________
C. 47p+, 60 n, 47 e- _________________
--------------------------------------
Elements, Compounds, and Formulas:--
* Elements>>> can exist as single atoms or molecules.
* Compounds>>> combination of two or more elements.
* molecular formulas for molecular compound.
*empirical formulas for ionic compounds.
Bulk Substances
* mainly ionic compounds
- empirical formulas
-structural formulas
Charge on Ions
*compounds have electrical neutrality.
*metals form positive monatomic ions.
*non-metals form negative monatomic ions.
Naming Binary Compounds
Common Compound:--s
H2O>>water
NH3>>ammonia
N2O>>nitrous oxide
CO>>carbon
monoxide
CS2>>carbon disulfide
SO3>>sulfur trioxide
CCl4>>carbon
tetrachloride
PCl5>>phosphor
pentachloride
SF6>>sulfur hexafluoride
Polyatomic Ions:-Ammonium>NH4+
Perchlorate>ClO4Cyanide>CNhydroxid OHNitrate>NO3Nitrite>NO2Nitride>N3-
Binary Ionic Compounds:-*Contain 2 different elements
*Name the metal first, then the nonmetal as -ide.
*Use name of a metal with a fixed charge
Groups 1A, 2A, 3A and Ag, Zn,cl
Examples:
sodium chlorid
NaCl
zinc iodide
ZnI2
aluminumoxide
Al2O3
Learning Check N1
Complete the names of the following binary compounds:
1/ Na3N
sodium ______________.
2/ KBr
potassium ____________.
3/ Al2O3
aluminum _____________.
4/ MgS
______________________.
Sulfate>SO42Carbonate>CO32Phosphate>PO43Floride>FChloride>ClBromide>BrIodide>I-
Names of Variable Ions:-Use a roman number after the name of a metal that forms two or more ions
Transition metals and the metals in groups 4A and 5A..
Examples>>
FeCl3
(Fe3+)
iron (III) chloride
CuCl
(Cu+ )
copper (I) chloride
PbCl2
(Pb2+)
lead (II) chloride
SnF4
(Sn4+)
tin (IV) fluoride
Learning Check N2
Name the following compounds:
A. CaO>>
B. SnCl4>>
1) calcium oxide .
3) calcium (II) oxide.
2) calcium(I) oxide.
1) tin tetrachloride.
3) tin(IV) chloride.
2) tin(II) chloride.
C. Co2O3 >> 1) cobalt oxide.
3) cobalt trioxide.
2) cobalt (III) oxide.
Learning Check N3
Complete the names of the following binary compounds with variable metal ions:
FeBr2
Cu2O
SnCl4
Fe2O3
CuS
iron (_____) bromide.
copper (_____) oxide.
___(_____ ) ______________
________________________
________________________
Naming Binary Covalent Compounds:-Two nonmetals
*Name each element
*End the last element in -ide
*Add prefixes to show more than 1 atom Prefixes
Mon >>> 1
Tetra >>> 4
Di
>>> 2
penta >>> 5
Tri >>> 3
hexa >>> 6
Learning Check N4
CO
carbon ______oxide.
CO2
carbon _______________
PCl3
phosphorus _______chloride
CCl4
carbon ________chloride.
N2O
_____nitrogen _____oxide.
Learning Check N5
A/ P2O5
1) phosphorus oxide
2) phosphorus pentoxide
3) diphosphorus pentoxide
B/ Cl2O7
1) dichlorine heptoxide
2) dichlorine oxide
3) chlorine heptoxide
C/ Cl2
1) chlorine
2) dichlorine
3) dichloride
--------------------------------------------------------. ‫تمنياتي لكم بالتوفيق والنجاح‬
10
-13
c
m
el
ec
tr
on
s
Valence of Metal Ions
Monatomic Ions
=> +1
Group IA
=> +2
Group IIA
Maximum positive valence
equals
Group A #
Valence of Non-Metal Ions
Monatomic Ions
=> -2
Group VIA
=> -1
Group VIIA
Maximum negative valence
equals
(8 - Group A #)