atom 1

KIMIA (PAI 08128) 2 KIMIA (PAI 08128) 2 SKSSKS

• MATERI KULIAH :1.Struktur atom2.Konfigurasi elektron 3.Sistem Berkala 4.Sifat periodik (potensial ionisasi, jari-jari atom,

afinitas elektron, keelektronegatifan) 5.Teori ikatan kimia6.Struktur molekul7.Sifat gas8.Zat padat dan kisi kristal9.Cairan 10.Asam basa11.Stoikiometri12.Hk. Termodinamika dan Termokimia

MATERIMATERI

Penilaian :Penilaian :

• Kuis : 20 %• Tugas terstruktur : 20 %• Kehadiran : 10 %• UTS : 25 %• UAS : 25 %

Atomic StructureAtomic Structure

Atomic Structure Atomic Structure Atom smallest particle of an element

capable of uncombined existence

Molecule is smallest unit of compound or substance; combination of 2 or more atoms

Contains exceedingly small nucleus with all of the + charge and most of total mass, protons, neutrons

Electrons equal in number to protons, negative charges surround nucleus

Hydrogen simplest ( 1 proton, 1 electron)

Helium next (2 protons, 2 electrons, 2 neutrons)

What are the 3 major parts What are the 3 major parts of an atom?of an atom?

What are the 3 major parts What are the 3 major parts of an atom?of an atom?

• Proton • Neutron • Electron

Draw a diagram showing the Draw a diagram showing the location of each part of the location of each part of the

atom.atom.

Draw a diagram showing the location Draw a diagram showing the location of each part of the atom.of each part of the atom.

http://www.eskom.co.za/nuclear_energy/fuel/fuel.html

Draw a diagram showing the Draw a diagram showing the charges of each part of the charges of each part of the

atom.atom.

Draw a Diagram of an Draw a Diagram of an AtomAtom

Draw a diagram showing the Draw a diagram showing the charges of each part of the atom.charges of each part of the atom.

Describe ProtonDescribe Proton

• Protons are positively charged particles found in the atomic nucleus. Protons were discovered by Ernest Rutherford..

Describe NeutronDescribe Neutron

• Neutrons are uncharged particles found in the atomic nucleus. Neutrons were discovered by James Chadwick in 1932.

Describe ElectronDescribe Electron

Electrons are negatively charged particles that surround the atom's nucleus. Electrons were discovered by J. J. Thomson in 1897.

Electrons determine properties of the atom. Chemical reactions involve sharing or exchanging electrons.

Describe NucleusDescribe Nucleus

The nucleus is the central part of an atom. It is composed of protons and neutrons.

The nucleus contains most of an atom's mass.

It was discovered by Ernest Rutherford in 1911.

Subatomic Particles

Particle Charge Mass (g) Location

Electron (e-) -1 9.11 x 10-28 Electron

cloud

Proton (p+) +1 1.67 x 10-24 Nucleus

Neutron (no) 0 1.67 x 10-24 Nucleus

Complete SymbolsComplete Symbols

• Contain the symbol of the element, the mass number and the atomic number.

X Massnumber

AtomicnumberSubscript →

Superscript →

Atomic NumberAtomic Number

• Atoms are composed of protons, neutrons, and electrons– How then are atoms of one element different

from another element?• Elements are different because they contain

different numbers of PROTONS• The “atomic number” of an element is the

number of protons in the nucleus• # protons in an atom = # electrons

Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element.

Element # of protons Atomic # (Z)

Carbon 6 6

Phosphorus 15 15

Gold 79 79

Atomic NumberAtomic Number

Mass NumberMass NumberMass number is the number of protons and neutrons in the nucleus of an isotope:

Mass # = pMass # = p++ + n + n00

Nuclide p+ n0 e- Mass #

Oxygen - 10

- 33 42

- 31 15

6 8 1616

Arsenic 75 33 75

Phosphorus 15 3116

EXAMPLE

How many protons, neutrons and electrons are found in an atom of

13355 Cs

Atomic number = protons and electronsThere are 55 protons and 55 electrons

Mass number = sum of protons and neutrons133 – 55 = 78There are 78 neutrons

HHydrogenHydrogen

1

1

Protons: 1Protons: 1Neutrons: 0Neutrons: 0Electrons: 1Electrons: 1

NaSodiuSodiumm

23

11

Protons: 11Protons: 11Neutrons: 12Neutrons: 12Electrons: 11Electrons: 11

– When an atom or molecule gain or loses an electron, it becomes an ion.•A cation has lost an electron and

therefore has a positive charge•An anion has gained an electron and

therefore has a negative charge.

SymbolSymbolAtomic MassAtomic Mass

Atomic NumberAtomic Number

Charge Charge (if ion)(if ion)

Na+

SodiuSodiumm

23

11

Protons: 11Protons: 11Neutrons: 12Neutrons: 12Electrons: 1Electrons: 100

SymbolsSymbols

Find each of these: a) number of protonsb) number of

neutronsc) number of

electronsd) Atomic numbere) Mass Number

Br80 35

If an element has an atomic number of 34 and a mass number of 78, what is the: a) number of protonsb) number of neutronsc) number of electronsd) complete symbol

SymbolsSymbols

If an element has 91 protons and 140 neutrons what is the a) Atomic numberb) Mass numberc) number of electronsd) complete symbol

SymbolsSymbols

If an element has 78 electrons and 117 neutrons what is the a) Atomic numberb) Mass numberc) number of protonsd) complete symbol

SymbolsSymbols

RheniumRhenium

Re186

75

Rhenium isotopeRhenium isotope

Re187

75

Isotop adalah atom-atom yang mempunyai nomor atom sama, tetapi nomor massanya berbeda.

– Contoh : ,

Isobar adalah atom-atom yang mempunyai nomor atom berbeda, tetapi nomor massanya sama.

– Contoh :

Isoton adalah atom-atom yang mempunyai nomor atom berbeda, tetapi jumlah neutronnnya sama.

– Contoh :

C126 C13

6

N146 N14

7

C136 N14

7

• Contoh soal– Tentukan jumlah proton dan neutron dalam

isotop-isotop berikut ini:

Mgdan Na,Na, N, N, C, C, H, H, , H 2412

2411

2311

157

147

146

126

31

21

11