PICLEC: MODULE 1 Flashcards
The science that describes matterβits properties, the changes it undergoes, and the energy changes that accompany those processes
CHEMISTRY
The CENTRAL SCIENCE
CHEMISTRY
Branches of Chemistry
- ORGANIC CHEMISTRY
- INORGANIC CHEMISTRY
- ANALYTICAL CHEMISTRY
- BIOCHEMISTRY
- PHYSICAL CHEMISTRY
BRANCH OF CHEMISTRY
- Hydrocarbons and its derivatives
ORGANIC CHEMISTRY
BRANCH OF CHEMISTRY
- Inorganic compounds, metals, minerals
INORGANIC CHEMISTRY
BRANCH OF CHEMISTRY
- Detection and identification of substances present (qualitative analysis) or amount of each substance (quantitative analysis)
ANALYTICAL CHEMISTRY
BRANCH OF CHEMISTRY
- Processes in living organisms
BIOCHEMISTRY
BRANCH OF CHEMISTRY
- Behavior of matter
PHYSICAL CHEMISTRY
Anything that has mass and occupies space; is tangible
MATTER
Measure of the quantity of matter
MASS
Amount of space
VOLUME
The capacity to do work or to transfer heat
ENERGY
TYPES OF ENERGY:
- KINETIC ENERGY
- POTENTIAL ENERGY
TYPES OF ENERGY
- Energy in motion
KINETIC ENERGY
TYPES OF ENERGY
- Energy at rest
POTENTIAL ENERGY
ENERGY CHANGES:
- EXOTHERMIC
- ENDOTHERMIC
ENERGY CHANGES
- Release (heat)
EXOTHERMIC
ENERGY CHANGES
- Absorbs (heat)
ENDOTHERMIC
STATES OF MATTER
- SOLID
- LIQUID
- GAS
STATES OF MATTER
- Molecules packed close together orderly; Rigid
SOLID
STATES OF MATTER
- Molecules are close but randomly arranged; Flows and assumes shape of container
LIQUID
STATES OF MATTER
- Molecules are far apart; Fills any container
completely
GAS
CHANGES OF STATES
S - L = MELTING
L - S = FREEZING
L - G = BOILING
G - L = CONDENSATION
G - S = DEPOSITION
S - G = SUBLIMATION
Can be observed or measured without changing the identity of the substance.
e.g. color, hardness, melting point, boiling point
PHYSICAL PROPERTIES
Exhibited by matter as it undergoes changes in
composition.
e.g. hydrogen has the potential to ignite and explode given the right conditions
e.g. iron reacts with oxygen gas to form rust
CHEMICAL PROPERTIES
Dependent on the amount of substance.
e.g. MASS β more substance, greater mass
e.g. VOLUME β more substance, greater volume
EXTENSIVE PROPERTIES
Independent on the amount of substance
e.g. DENSITY, Electrical Conductivity
INTENSIVE PROPERTIES
Way to Tell Intensive and Extensive Properties Apart
βͺ Take two identical samples of a substance and put them
together.
βͺ If this doubles the property (e.g., twice the mass, twice as
long), itβs an extensive property.
βͺ If the property is unchanged by altering the sample size,
itβs an intensive property.
- one or more substances are used up
- one or more new substances are formed,
- energy is absorbed or released
- IRREVERSIBLE
- e.g. burning of paper, cooking an egg, souring of milk
CHEMICAL CHANGE
- no change in chemical composition
- REVERSIBLE
- e.g. shredding paper, boiling of water, breaking a
bottle
PHYSICAL CHANGE
Variable Composition (e.g. 70%, 80% or 95% ethanol in water)
May be separated into pure substances by physical methods (e.g. distillation, filtration)
MIXTURE
Fixed composition (e.g. 100% ethanol)
Cannot be separated into simpler substances by physical methods
PURE SUBSTANCE
- Components are NOT distinguishable (single phase)
- Have same composition throughout (i.e. same amount
in any areas) - e.g. SOLUTION
HOMOGENEOUS MIXTURE
- Components are distinguishable (multiple phases)
- Do NOT have same composition throughout (i.e.
different amount in various areas) - e.g. SUSPENSION
HETEROGENEOUS MIXTURE
- Can be decomposed to simpler substance by
chemical changes - consists of atoms of two or more different elements
bound together. - e.g. water, H2O can be broken into hydrogen and
oxygen gases via electrolysis
COMPOUND
- Cannot be decomposed to simpler substance by chemical changes
- Consists of only one kind of atom
ELEMENTS
- The smallest unit that retains the properties of an element.
ATOM
- All matter is composed of atoms and these cannot be made or destroyed.
DALTONβS THEORY
The number of protons in the nucleus of
an atom determines its identity; this
number is known as the atomic number
of that element.
e.g.
- Hydrogen atom contains 1 proton.
- Lithium atom contains 3 protons.
ATOMIC NUMBER (Z)
The mass number of an atom is the sum of the number of
protons and the number of neutrons in its nucleus; that is
π΄πππ π΅πππππ = # ππ π + # ππ π
π΄πππ π΅πππππ = π¨πππππ π΅πππππ + π΅ππππππ π΅πππππ
MASS NUMBER (A)
Isotopes are atoms of the SAME ELEMENT with DIFFERENT MASSES
They are atoms containing the same number of protons but different numbers of neutrons.
ISOTOPES
Represents the composition of the nucleus
NUCLIDE SYMBOL
SAME MASS NUMBER - DIFFERENT ATOMIC NUMBER
ISOBARS
SAME NEUTRONS - DIFFERENT ATOMIC NUMBER
ISOTONES
Many elements occur in nature as mixtures of isotopes.
The atomic weight of such an element is the weighted average of the masses of its isotopes.
Atomic weights are fractional numbers, not integers.
ATOMIC WEIGHT
- Greek word βAtomosβ β uncuttable
- Atom as solid indivisible sphere
LEUCIPPUS AND DEMOCRITUS
- Matter is made up of four elements
ARISTOTLE AND OTHERS
- Solid Sphere (Billiard Ball) Model
- Atom as solid sphere but
NOT indivisible
DALTONβS ATOMIC THEORY
JOHN DALTON
DISCOVERY OF ELECTRONS
βͺ Elements of a chemical compound are held together by
electrical forces.
- Humphry Davy (1800s)
βͺ Relationship between the amount of electricity used in
electrolysis and the amount of chemical reaction that
occurs.
- Michael Faraday (1832)
βͺ βElectronsβ β Electric ions
- George Stoney (1891)
Elements of a chemical compound are held together by
electrical forces.
HUMPHRY DAVY
Relationship between the amount of electricity used in electrolysis and the amount of chemical reaction that occurs.
MICHAEL FARADAY
βElectronsβ β Electric ions
GEORGE STONEY
The Discovery of Electrons
- CATHODE RAY TUBE
- OIL- DROP EXPERIMENT
- SATURN LIKE MODEL
The Discovery of Electrons
- Joseph John Thomson (1897)
- Most convincing evidence of electrons
- Plum pudding model
CATHODE-RAY TUBE EXPERIMENT
The Discovery of Electrons
- Robert Millikan (1909)
- Determine the charge of electrons
OIL-DROP EXPERIMENT
The Discovery of Electrons
- Hantaro Nagaoka (1903)
SATURN-LIKE MODEL
The Discovery of Protons
- CANAL RAYS EXPERIMENT
- SCATTERING EXPERIMENT
- NUCLEAR MODEL
The Discovery of Protons
- Eugen Goldstein (1886)
- Cathode-ray tube also generates a stream of
positively charged particles
- These positive rays, or positive ions, are created
when the gaseous atoms in the tube lose electrons.
CANAL RAYS EXPERIMENT
The Discovery of Protons
- Ernest Rutherford (1910)
Assumption:
- If the Thomson model of the atom were correct, any
alpha-particles passing through the foil would have
been deflected by very small angles.
- Quite unexpectedly, nearly all of the a-particles
passed through the foil with little or no deflection.
Rutherfordβs Conclusion:
- Atoms consist of very small, very
dense positively charged nuclei
surrounded by clouds of electrons
at relatively large distances from
the nuclei.
SCATTERING EXPERIMENT
The Discovery of Protons
- Positive charge localized in the NUCLEUS
NUCLEAR MODEL
The Discovery of Neutrons
- BOHRβ S MODEL
- BOHRβS PLANETARY MODEL
The Discovery of Neutrons
- Each orbit thus corresponds to a definite energy level
for the electron.
- When an electron is excited from a lower energy level
to a higher one, it absorbs a definite (quantized)
amount of energy.
- Electrons occupy only certain energy levels in atoms.
BOHRβS PLANETARY MODEL
Studied X-rays given off by various
elements.
H.G.J. MOSELEY
Bombardment of beryllium with high-energy alpha-particles produced NEUTRONS
JAMES CHADWICK
Described the electron of a hydrogen atom as revolving around its nucleus in one of a discrete set of circular orbits.
NIELS BOHR
- Proposed the idea of wave-like nature of electrons
βͺ Electrons can be treated as waves more effectively than
as small compact particles traveling in circular or elliptical
orbits.
LOUIS DE BROGLI
Based on the wave properties of matter
QUANTUM MECHANICS
- For electrons, it is not possible to determine the exact momentum and the exact position at the same moment in time.
WERNER HEISENBERGβS UNCERTAINTY PRINCIPLE
It estimates the position of electrons and quantifies energy levels.
ERWIN SCHRΓDINGERβS WAVE EQUATION
A region of space in which the probability of finding an electron is high.
ATOMIC ORBITALS
Erwin SchrΓΆdinger
- Electron Cloud Model
- Quantum Mechanical Model
MODERN ATOMIC MODEL
QUANTUM NUMBERS
- Principal QN (π)
- Orbital QN (π)
- Magnetic QN (ππ)
- Spin QN (ππ)
- for individual electrons only
βͺ π = π, π, π, β¦ (π)
βͺ Orbital β SHELL or ENERGY LEVEL
βͺ Distance of the electron
from the nucleus
βͺ Higher π, higher energy
PRINCIPAL QUANTUM NUMBER (n)
βͺ a.k.a. Azimuthal or Orbital Angular momentum Quantum
Number
βͺ π = π, π, π, π, β¦ (π β π)
βͺ Orbital β SUBSHELL/ SUBLEVEL
βͺ Shape of the orbital
- π = π s spherical
- π = π p dumb-bell
- π = π d clover leaf
- π = π f complex
ANGULAR/ORBITAL MOMENTUM QUANTUM NUMBER
βͺ ππ = βπ β¦ π β¦ + π
βͺ Orbital β Specific orbital
βͺ Orientation in space of the orbital
MAGNETIC QUANTUM NUMBER
βͺ For each INDIVIDUAL ELECTRON only
βͺ ππ = + π/π , - π/π
βͺ Direction of spin (clockwise or counter-clockwise)
βͺ Quantum Number and Electron Configuration
SPIN QUANTUM NUMBER
βͺ βDistribution of electronsβ
βͺ describes the number and arrangement of electrons in
orbitals, subshells and shells in an atom.
βͺ Ground state
- Atom in its lowest energy, or unexcited, state.
ELECTRON CONFIGURATION
- Orbitals fill in order of increasing energy, from lowest to highest.
AUFBAU PRINCIPLE
- No more than two electrons can occupy each orbital, and if two electrons are present, they must have opposite spins.
PAULI EXCLUSION PRINCIPLE
- The order of fill is the same but as you can see from
above the electrons are placed singly into the boxes
before filling them with both electrons. - A single electron will occupy an empty orbital first
before pairing.
HUNDβS RULE
Arranged the periodic table based on chemical properties
DIMITRI MENDELEEV
Arranged the periodic table based on physical properties
LOTHAR MEYER
βͺ Both emphasized the periodicity, or regular periodic
repetition of properties with increasing atomic weight.
DIMITRI MENDELEEV AND LOTHAR MEYER
- βThe properties of the elements are periodic functions
of their atomic numbers.β
βͺ Vertical Columns β Groups or Families
βͺ Horizontal Rows β Periods
PERIODIC LAW
High electrical conductivity that decreases with increasing temperature
METALS
High thermal conductivity
METALS
Malleable, Ductile, silver luster, forms cat ions by losing electrons, form ionic compounds with non metals, solid state characterized by metallic bonding
METALS
Poor electrical conductivity
NON METALS
Good heat insulators
NON METALS
Brittle, non-ductile, no metallic luster, form anions by gaining electrons, form ionic compounds with metals and molecular compounds with non metals, covalently bonded molecules
NON METALS
- Show some properties that are characteristic of both
metals and non-metals - Semiconductors
βͺ insulators at lower temperatures but become
conductors at higher temperatures
βͺ silicon, germanium, and antimony
METALLOIDS
PERIODIC PROPERTIES OF ELEMENTS
- Defined as half of the distance between the nuclei of neighbouring atoms in the pure element
- Expressed in Angstroms (1Γ
= 10-10 m)
ATOMIC RADII (size)
PERIODIC PROPERTIES OF ELEMENTS
- The energy required to remove an electron from a gas-phase atom
IONIZATION ENERGY (IE)
PERIODIC PROPERTIES OF ELEMENTS
- The energy change that occurs when an electron is attached to an atom in the gas phase to form an negative ion
ELECTRON AFFINITY (EA)
PERIODIC PROPERTIES OF ELEMENTS
- Measure of the relative tendency of an atom to attract electrons to itself when it is chemically combined with another atom
ELECTRONEGATIVITY (EN)
same mass no. different atomic no.
ISOBARS
same elements different mass no.
ISOTOPES
same neutrons different atomic no.
ISOTONES
