Cheatography

# Structure of an Atom Cheat Sheet (DRAFT) by Ayesha Talib

This is a draft cheat sheet. It is a work in progress and is not finished yet.

### CHARAC­TER­ISTICS OF SUB-ATOMIC PARTICLEES

 PROPERTY ELECTRON PROTON NEUTRON DISCOVERY JJ Thomson E Goldstein Chadwick ABSOLUTE MASS 9×10-31kg 1.6×10-27kg 1.6×10-27kg RELATIVE MASS 1/1840u 1u 1u CHARGE negative positive no charge ABSOLUTE CHARGE -1.6×10 −19 +1.6×10 −19 0 LOCATION outside nucleus inside nucleus inside nucleus

### THOMSON'S MODEL

 limita­tions of JJ's model of an atom? couldn't explain stability of an atom, neutron & nucleus. acc. to him, mass of atom was uniformly distri­buted but mass is concen­trated in the nucleus. results of experi­ments by scientists couldn't be explained by this model. explain his model. an atom consists of a +vely charged sphere and e- are embedded in it. -ve & +ve charges are equal in magnitude, so the atom is electr­ically neutral.

### RUTHER­FORD'S MODEL

 any particle in a circular orbit would undergo acc.. during accn, charged particles would radiate energy. thus, revolving electrons would lose energy and fall into the nucleus. thus the atoms would be highly unstable but they're not.

### BOHR'S MODEL

 only certain special orbits known as discrete orbits of e-, are allowed inside atom. while revolving, e- don't radiate energy. these energy shells are repres­ented by letters K,L,M,N.. or numbers n=1,2,­3,4..

### ATOMIC & MASS NUMBER

 atomic number = total Np OR Ne ex; Na: 11, Np OR Ne = 11 mass number = Np+Nn [neuclons] average atomic mass = mass no.×pe­rce­nta­ge+mass no.×pe­rce­ntage

### ISOTOPES /\ ISOBARS

 atoms of the same element having same atomic numbers but different mass numbers atoms of different elements with different atomic numbers but same mass numbers have same chemical properties but different physical properties have different chemical properties but same physical properties ex; 12``6``C 14``6``C ex; 40``20``Co 40``18``Ar
isotope of: uranium- fuel in nuclear reactors; cobalt- treatment of cancer; iodine- treatment of goitre.

### ELEMENTS & NEUTRONS

 1. H: 0 7. N: 7 13. Al: 14 2. He: 2 8. O: 8 14. Si: 14 3. Li: 4 9. F: 10 15. P: 16 4. Be: 5 10. Ne: 10 16. S: 16 5. B: 6 11. Na: 12 17. Cl: 18 6. C: 6 12. Mg: 12 18. Ar: 22

### SYMBOLS OF IONS

 Sodium Na+ Potassium K+ Silver Ag+ Copper [I] Cu+ Magnesium Mg2+ Calcium Ca2+ Zinc Zn2+ Iron [II] Fe2+ Copper [II] Cu2+ Aluminium Al3+ Iron [III] Fe3+

### SYMBOLS OF IONS [non-m­etallic elements]

 Hydrogen H+ Hydride H- Chloride Cl- Bromide Br- Iodide I- Oxide O2- Sulphide S2- Nitride N3-

### SYMBOLS OF IONS [polya­tomic ions]

 Ammonium NH``4``+ Hydroxide OH- Nitrate NO``3``- Hydrogen Carbonate HCO``3``- Carbonate CO``3``2- Sulphite SO``3``2- Sulphate SO``4``2- Phosphate PO``4``3-