ChemistryChemistry

ChemistryChemistry

Chemistry is the study of the composition, properties, andtransformations of matter.

2N CO2 + 2 N H2O + PHOTONS → 2(CH2O)N + 2N O2 CARBON DİOXİDE + WATE R + LİGHT ENERGY → CARBOHYDRATE + OXYGEN

C6H12O6 + 6O2 → 6H 2O +6CO2+energy

Text Book : Genelral Chemistry, R. H. Petrucci, W.S. Harwood, Prentice Hall International, Inc., 2002, 8th Ed.

Chemistry a molecular approach Nivaldo J Tro Pearson Education 2008 and all other chemistry books

1st Midterm : 7 Nov. 2009 Saturday 10-12 (Topic: 1,2,3,4,5,6,7,9,10)2nd Midterm : 19 Dec. 2009 Saturday 10-12 (Topic: 11,12,13,14 )Final : All topics

Grading: 1st Midterm 25%, 2nd Midterm %25, and Final 50 %

KIM 101E General ChemistryMustafa Özcanhttp://www.kimya.itu.edu.tr

WEEK DATE TOPICS1 1 Oct. 2009 Electronic Structure of Atom (Chp:1-2-9)

2 /08 Oct. 2009 Periodic Table, Chemical Compounds (Chp:10 ve 3)

3 15 Oct. 2009 Chemical Reactions, Reactions in Aqueous Solutions (Chp:4 ve 5)

4 22 Oct. 2009 Gases (Chp:6)

5 29 Oct. 2009

6 05 Nov. 2009 Thermochemistry (Chp:7)

7 Nov. 2009 1st Midterm (Topic: 1,2,3,4,5,6,7,9,10)

7 12 Nov2009 Chemical Bonding –I (Chp:11)

8 19 Nov 2009 Chemical Bonding –II (Chp:12)

9 26 Nov 2009

10 03 Dec. 2009 Liquids, Solids, and Intermolecular Forces (Chp:13)

11 10 Dec. 2009 Liquids, Solids, and Intermolecular Forces (Chp:13)

12 17 Dec. 2009 Solutions and Their Physical Properties (Chp:14)

19 Dec. 2009 2nd Midterm (Topic: 11,12,13,14)

13 24 Dec. 2009 Chemical Equilibrium (Chp:16)

14 31 Dec. 2009 Acids and Bases (Chp:17)

MATTER

is anything that occupies space and has mass All matter is formed from one or more of 114 presentlyknown elements—fundamental substances

Early Chemical Discoveries Antonie Lavosier: LAW OF MASS CONSERVATION Mass is neither created nor destroyed in chemical

reactions.

French chemist Joseph Proust: LAW OF DEFINITE PROPORTIONS Different samples of a pure chemical substance

always contain the same proportion of elements by mass

John Dalton (1766–1844), proposed a new theory of matter as follows: Elements are made of tiny particles called atoms. Each element is characterized by the mass of its atoms. Atoms of the same element have the same mass, but atoms of different elements have different masses. Chemical combination of elements to make different substances occurs when atoms join

together in small whole-number ratios. Chemical reactions only rearrange the way that atoms are combined; the atoms themselves are

unchanged.

Subatomic particles.

1897 J.J Thomson proposed that cathode rays must consist of tiny negatively charged particles, which we now call electrons. Thomson was able to calculate the ratio of the electron’s electric charge to its mass—its charge-to-mass ratio, e/ m = 1.758 820 x 108 C/g

Robert Millikan found mass of electron as 9.109 382 x 10-28 g by oil drop experiment

Ernest Rutherford found that atoms also contain positively charged particles. in 1911

Rutherford proposed that most of the mass and positive charges of an atom are concentrated in a tiny central core that he called the nucleus.

1932 James Chadwick discovered some subatomic particles other than protons named neutrons.

Particle name

Symbol Electric ChargeCoulomb C

Relative Electric Charge

Mass g Atomic mass unit

Location

Proton p+ +1.602 x 10-19 +1 1.673x10-24 1.0073 Inside nucleus

Neutron n 0 0 1.675x10-24 1.0087 Inside nucleus

Electron e- -1.602 x 10-19 -1 9.109x10-28 0.00055 Outside nucleus

Subatomic particles.

A X Z

Atomic number Z = Number of protons in atom’s nucleus= Number of electrons around atom’s nucleus

A = Z + N.

Mass number (A) = Number of protons (Z) + Number of neutrons (N)

İsotopes : atom with the same number of protons but different numbers of electrons are called isotope

1 H1 2 H 13 H1

A (p-e)

X Z

Ion: an atom or group of atoms which either positevely charged or negatively chargedAs a result of the loss or gain of electrons

Electrons in Atom

Lights has many characteristics in common with electrons

Light is a kind of electromagnetic wave carrying energy. ( Waves can be identified as a motion carrying energy)

• The wave nature of light• The particle nature of light

The wavelength () is the distance between any two identical points in consecutive cycles.

The frequency () is the number of wave cycles that pass a point each second. Its unit is 1/second (Hertz) .

The amplitude of a wave is its height

Unit Symbol (m)

Angstrom Å 10-10

Nanometre nm 10-9

Mikrometre m 10-6

Millimetre mm 10-3

sentimetre cm 10-2

Metre m 1

the velocity of a wave is the product of its frequency and its wavelength, for light c = .

Elektromagetic spectra

• question: calculate the frequency, in s-1, of an X-ray that has a wavelength of 8.21nm

Particlelike Properties of ElectromagneticRadiation:

• Quantum theory: (1900 The Planck Equation) E= h. . = h c / h=Planck constant = 6.626 x 10-34 J.s

• Photoelectric effect : ( 1905 Albert Einstein)

When a beam of light shines on certain surfaces particularly certain metals, e beam of electrons is produced. This phenomenon is called the photoelectric, Einstein considered that electromagnetic radiation has particle like characteristics and that particles of light called photons, posses a characteristic energy, given by planck’s equation.

calculate the energy of X ray having 8,21nm vawelength

calculate the energy of the violet light that has 6,15x1014s-1 frequency

Arrange the followings in order to increasing vawelength and energy per photon

a- X-Ray

b- UV

c- Visible light

d- Microwave

e- Infrared

• A nitrogen gas laser pulse with wavelength of 337nm contains 3.83mJ of energy. How many photons does it contain?

Bohr Atom Theory

En = - Rh / n2

Rh= 2.179 x 10 –18 J

En = - Rh / n2

Rh= 2.179 x 10 –18 J

= RH ( ni2

1

nf2

–1

) = h = hc/λ

ΔE = Ef – Ei = -RH

nf2

-RH

ni2

–

• Calculate the energy change in electron transition from Hirojen n=5 to n=3 in hydrogen atom

• Determine the wavelength of light emitted when an electron in a hydrogen atom Hiydrogen atom makes a transition from an orbital n=6 to n=5.

Bohr Atom Theory

• the electrons in an atom move at a certain distance from nucleus and their motions are stable . Each stationery state has a definite energy.

• Electrons move in each stationary energy state in a circular orbital. These circular orbitals are called energy levels or shells. The possible states for the electron are numbered, n=1, 2, 3 and so on.

• When an electron is in a stationary state, the atom does not emit light. However when an electron falls back to a lower energy level from a higher one, it emits a quantum of light that is equal to the energy differences between these two energy levels.

the Heisenberg Uncertainty Principle

• imagine what would happen if we tried to determine the position of an electron at a given moment. For us to “see” the electron, light photons of an appropriate frequency would have to interact with and bounce off the electron. But such an interaction would transfer energy from the photon to the electron, thereby increasing the energy of the electron and making it move faster. Thus, the very act of determining the electron’s position would make that position change. In mathematical terms, Heisenberg’s principle states that the uncertainty in

• the electron’s position, times the uncertainty in its momentum, is equal to or greater than the quantity h/4p:

Δx Δp ≥ h

4π h

= ------------- DE BROGLIE EQUATION

m.

the mass of an electron is 9,109x10-28g and its velocity 5,97x106 m/s,

what is the wavelength of this electron?

Quantum Numbers

The principal quantum number (n) is a positive integer on which the size and energy level of the orbital primarily depend. n= 1, 2, 3,4, 5,6,7

The angular-momentum quantum number (l) defines the three-dimensional shape of the orbital. l can have any integral value from 0 to n-1

If n = 1, then l = 0 2If n = 2, then l = 0 or 1 If n = 3, then l = 0, 1, or 2

The magnetic quantum number (ml)defines the spatial orientation of theorbital with respect to a standard set of coordinate axes. Ml can have any integral value

ml = from -l to + l .

spin quantum number electrons behave as if they were spinning around an axis,much as the earth spins daily. Unlike the earth, though, electrons are free to spin in either a clockwise or a counterclockwise direction. This spinning charge gives rise to a tiny magnetic field and to a spin quantum number (which can have either of two values, -1/2 or +1/2)

s orbitals p orbitals d orbitals f orbitals

l= 0 I =1 l =2 l =3

ml= 0 ml= -1,0,+1 ml =-2,-1,0,+1,+2 ml= -3,-2, 1,0,+1,+2,+3

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

s p d f

max e: 2 max electron: 6 max electron:10 max electron: 14

Electron Configurations of Multielectron Atoms

- Lower-energy orbitals fill before higher-energy orbitals.1s -2s -2p -3s- 3p –4 s-3d -4p -5s -4d -5p –6s-4f –5d -6p -7s -5f

-6d (Aufbau),

• no two electrons in an atom can have the same four quantum numbers. In other words, the set of four quantum numbers associated with an electron acts as a unique “address” for that electron in an atom, and no two electrons can have the same address.(Pauili)

• HUND’S RULE If two or more orbitals with the same energy are available, one electron goes in each until all are half-full. The electrons in the half-filled orbitals all have the same value of their spin quantum number.

Diamagetic: the state of an atom or ion that contains only paired electrons

Paramagnetic: the state of an atom or ion that contains only unpaired electrons

İsoelektronic: atoms or ions which have the same numbers of electron are isoelectronic. (same electron configuration)

Question: which one shows the quantum numbers of last electron of Neutral Na atom has the elecron configuration as 1s2 2s2 2p6 3s1

a- n=1 l=0 ml=0 ms= +½

b- n=3 l=1 ml=0 ms= +½

c- n=3 l=0 ml=1 ms= +½

d- n=1 l=1 ml=1 ms= +½

e- n=3 l=0 ml=0 ms= +½

Soru: which one has the paramagnetic properties

a- 2He

b- 18Ar

c- 20Ca

d- 30Zn

e- 40Zr

explain the following quantum numbers are possible or not?

a. n=3 l=2 ml=-1

b. n=3 l=3 ml=-3

c. n=2 l=3 ml=-1

d. n=5 l=2 ml=-1