Kuliah ke-5. Struktur Atom.ppt perkuliahan kimia dasar

materi kuliah kimia dasar

1. STRUKTUR ATOM
1
Rangkaian Elektronik Instrumen Kimia

2. TEORI ATOM
1.Teori Atom Thomson
Atom seperti roti kismis, yang
permukaannya dipenuhi dengan muatan +
dan -
Sinar Sinar 
++
++
--
++
++
++
++
--
--
--
--
--
++
--HeHe
Pembuktian teori dengan menembakan sinar 
--
2

3. 2.Teori Atom Rutherford
Teori ini mengemukakan massa atom terpusat di
inti yang bermuatan positif. Elektron terletak di
luar inti pada jarak yang relatif jauh dengan
gerakan yang cepat
Sinar Sinar 
Gaya tarik elektron dan inti diimbangi oleh gaya
tarik sentrifugal
ee ee
ee ee
3

4. Menurut hukum fisika klasik, partikel
bermuatan yang bergerak selalu kehilangan
energi dengan demikian gerakan elektron
makin mendekati inti dan terjadi gerakan
spiral dengan kecepatan menurun. Pada
suatu saat elektron bergabung dengan inti
dan atom akan musnah. Dalam
kenyataannya atom tidak musnah
4

5. 3.Teori Atom Bohr
Kesukaran pada teori atom Rutherford diatasi oleh
Bohr. Gerakan elektron mengelilingi inti harus
dengan momentum sudut tertentu.
1.Elektron dalam lintasannya mempunyai energi
tertentu dan tetap selama dalam lintasan
2.Elektron dapat pindah dari lintasan yang
energinya lebih tinggi ke lintasan yang energinya
lebih rendah. Bila hal ini terjadi, energi yang
terbebas diubah menjadi sinar dengan frekuensi
h
EE
v
12
-

5

6. EE
11
EE
22
EE
33

π2

π2

h
nmv
nh
mv 
mv = momentum sudut
Energinya dinyatakan

c
hvh . . E 
E
1 = E
2 -
E
1 = h.v
1
E
2
= E
3
-

E
1
= h.v
2
Sinar-sinar dengan frekuensi v
1
dan v
2

menyebabkan terjandinya spektra garis
6

7. 3.1 Partikel sub Atom3.1 Partikel sub Atom
 ElektronElektron
FIGURE FIGURE 33.1.1 (a) (a) A gas discharge tube. A gas discharge tube. (b) (b)
Deflection of a cathode ray toward a positively Deflection of a cathode ray toward a positively
charged platecharged plate
7

8.  Percobaan Millikan: Penentuan Massa ElektronPercobaan Millikan: Penentuan Massa Elektron
FIGURE FIGURE 33..33
Millikan’s Millikan’s
famous oil famous oil
drop drop
experimentexperiment
C/g 10 x 1,76 -
m
e
8

e =e = - 1,60 x 10 - 1,60 x 10
1919
C C g 10 x 9,09
C/g 10 x 1,76 -
C 10 x 1,60

28-
8
-19

m
8

9. FIGURE FIGURE 33..44 Positively charged particles are made when Positively charged particles are made when
cathode rays (electrons) strike atoms of residual gas. They are cathode rays (electrons) strike atoms of residual gas. They are
attracted to the cathode, and some sail through the hole to strike attracted to the cathode, and some sail through the hole to strike
the phosphor and generate a flash of lightthe phosphor and generate a flash of light
 ProtonProton
9

10. ProtonProton
NeutronNeutron
FIGURE FIGURE 33.8 .8
The protons and neutrons of an atom are packed in The protons and neutrons of an atom are packed in
an extremely small nucleus Electrons are shown as an extremely small nucleus Electrons are shown as
"clouds" around the nucleus. "clouds" around the nucleus.
10

11. 3.2 Radiasi elektromagnetik dan
spektrum atom. tingkatan energi
dalam atom.
FIGURE 3.9
Atoms not drawn to
scale, as they are
joined in water, H
2
O
Nuclei stay far apart
and only the outer
parts of the atoms
touch
11

12.  Energi ElektromagnetEnergi Elektromagnet
FIGURE FIGURE 33.10.10 The electrical force assocThe electrical force assocIaIated wted wiitthh
electromagnetic radiation fluctuateelectromagnetic radiation fluctuatess rhythmically. rhythmically. (a) (a) Two Two
cycles of cycles of fflucluctutuaation are tion are shshown; therefore. the frequency is 2 own; therefore. the frequency is 2
Hz. Hz. (b) (b) An electromagneticAn electromagnetic ra radiation frozen in time. This curve diation frozen in time. This curve
shows how the electricshows how the electricalal force varies alo force varies alonng thg thee d diirerecction of tion of
travel. travel. The distThe distance ance between two maximum values ibetween two maximum values iss the the
wavelewavelenngth of the egth of the ellectectrromaomaggnetic radnetic radiiatiatioon. n.
12

13. The SI symbol for the The SI symbol for the secondsecond is is ss. .
SS
-1-1
= = 11//ss
For any wave, the product of its wavelength For any wave, the product of its wavelength
and its frequand its frequeency ncy eequaqualls ths thee velocity of the velocity of the
wave. wave.
HertzHertz ==(Hz)(Hz)
1 Hz1 Hz = = 11ss
-1-1

LamdaLamda = =  = Panjang Gelombang = Panjang Gelombang
KecKec.. Cahaya Cahaya = = c c = 3,00 x 10= 3,00 x 10
88

mmss
-1-1

 . . = = c c = 3= 3,,00 x 1000 x 10
88
m mss
-1-1

13

14. FIGURE 3.11 The electromagnetic spectrum
 Spektrum Elektromagnetik
14

15. FIGURE 3.14 Production of a line spectrum. The light emitted by excited
atoms is formed into a narrow beam and passed through a prism. This
light beam is divide into relatively few narrow beams with frequencies that
are characteristic of the particular eIement that is emitting the light.
 Spektrum Atom
15

16. Spektrum Unsur
16

17. 3.4 Gelombang Elektron dalam Atom
2
-
n

L
Orbital = bentuk gelombang elektron
 Bilangan Kuantum Utama = n
n = 1 - ~
n 1 2 3 4 ...
Kulit K L M N ...
 Bilangan kuantum kedua = l = sub kulit bilangan kuantum
azimuth.
Untuk setiap harga n; l = O sampai dengan l = n -1
l 01 2 3 4 5 …
Sub Kulit s p d f 9 h …
17

18. 1 0
2 0,1
3 0, 1, 2
4 0, 1, 2, 3
5 0, 1, 2, 3, 4
TABLE 3.1 Relationship between n and l
Value of nValue of n Value of Value of l
4s < 4p < 4d < 4f
Energi bertambah besar
 Bilangan Kuantum Magnet = ml
Untuk setiap harga l, harga ml adalah -1 s/d +1
18

19. 3.5 Spin Elektron = ms
ms = + ½ atau – ½ Prinsip Pauli
19
Pauli received the 1945 Nobel
Prize in physics for his discovery
Of the exclusion principle.

20. A paramagnetic A paramagnetic
substance is attracted to substance is attracted to
a magnetic fielda magnetic field
20

21. 3.6. Konfigurasi Elektron = Struktur Elektronik
21

22. Aturan Hund :
FIGURE 3.18 A way
to remember the fiIling
order of subshells.
Write the subshell
designations as shown
and follow the diagonal
arrows, starting at the
bottom.
Core Elektron: Na [Ne] 3s
1
Mg [Ne] 3s
2

22

23. 3.10. Energi lonisasi = EA
Adalah energi yang diperlukan untuk melepaskan
satu elektron dari atom yang terisolasi.
X
(g)
X
-
(g)
+ e
23
FIGURE 3.27FIGURE 3.27 The variation of first ionization energy with atomic numberThe variation of first ionization energy with atomic number

24. 3.11. Afinitas Elektron = EA
Adalah energi yang dilepaskan untuk menerima
satu elektron dari atom yang terisolasi.
X
(g)
+ e
-
X
-
(g)

24