atoms Flashcards
What is the structure of atoms? and what are there properties?
- Proton’s have a relative charge of +1, have a mass of 1 and are located in the nucleus.
- Neutron’s have a relative charge of 0, have a mass of 1 and are located in the nucleus.
-Electron’s have a relative charge of -1, have a mass of 1/1840 and are located in the shells.
How are element’s set out? fact’s about the periodic table?
The atomic number of an element is equivalent to the proton’s which is equivalent to the electron’s . the relative atomic mass also know as the moler mass is equivalent to proton - neutrons. and any element’s that are in group 7 come in pair and they are called diatomic.
What are ion’s?
Ion’s come from atoms. metal atom’s lose electron’s to become a positive charge and non-metal gain electron’s to become a negative charge.
What are isotope?
Q. What are the similarities and differences(79Br and 81Br)?
[Atom’s of the same element that have the same number of proton’s and electron’s but have a different number of neutron’s] They also have the same chemical properties as the same element’s.
A. 79Br and 81Br are similar with the same amount of proton’s and electron’s they have but are different in that 81Br has two more neutron’s than 79Br.
what is relative atomic mass (Ar) / Moler mass?
Q. chlorine gas has a Rm of 35.5
[The average mass of an atom relative to the mass of one twelfth of a carbon-12 atom]
A. chlorine atom mass is 35.5 times heavier than 1/12 of carbon-12
What is relative molecular mass (Mr) and how is it calculated?
Q. C6H1206
[The mass of a molecule relative to the mass of one twelfth of a carbon-12 atom]
A. C=12X6=72 H=1X12=12 O=16X6=96
72+12+96=180g/mol
What is the relative formula mass? How does it differ from Molecular mass? How is it worked out?
Q. Ca(NO3)2
[The mass of a molecule relative to the mass of one twelfth of a carbon-12 atom]. Relative formula mass is the term used when a compound has a giant structure.
A. Ca N2 O6
Ca=1x40.1=40.1 N=2x23=46 O=6x16=96
40.1+46+96=182.1g/mol
What is the relative isotopic mass? what is it need for? and how is it calculated?
[The mass of one atom of a particular isotope relative to the mass of one twelfth of carbon-12 atom]. Relative isotopic mass is need for calculating the relative atomic mass also the abundances in also needed (usually %)
mass x percentage of mass/100 + mass x percentage of mass/100
is the abundance is a fraction than it is 1/? x mass of element
What is the mole?
[One mole of a substance is the mass that has the same number of particles are there are in exactly 12g of carbon-12]
Mole = 6.02x10^23.
When is Avogadro’s constant (Na) needed? and how is it worked out?
When a question have atom’s, ion’s or molecule’s involved you have to use Avogadro’s constant.
Number or Particle’s = No of mole’s X Na (6.02x10^23)
What is moler mass? and how is it worked out?
Q. M(Cl-35)
M(CaC03)
[The mass of one more of a substance] units are g/mol-1
A. M(Cl-35) = 35 g/mol-1
M(CaC03) = 100.1 g/mol-1
Q. Solid sulfur exists as a lattice of S8 molecules. Each S8 is a ring of 8 atoms. How many atoms of sulfur are there in 0.0120 mol of s8 molecules.
A. 0.0120 x 6.02x10^23=7.224 x 10^21 of S8 7.224 x 10^21 x 8 = 5.7792 x 10^22
What is empirical formula and how is it calculated?
Q. 0.477 g of Oxide iron was reduced. 0.345 g of iron was produced. calculate the empirical formula.
[the simplest whole number ratio of the number of atoms of each element in a compound]
A. Fe + O –> FeO 0.345 g + 0.132 g –> 0.477 g
Fe O
0.345/55.8 0.132/16
=0.006/0.006 =8.25x10^-3/0.006
=1 =1.375
1:1.375 x 3 = 3:4 = Fe3O4
What is molecular formula? and how is it worked out?
Q. A hydrocarbon has a empirical formula of CH2 and a relative molecular mass of 112 - what is it molecular formula?
Compound A is a liquid hydrocarbon of relative molecular mass 78 and contains 92.3% carbon. Calculate the molecular formula of A.
[Shows the total number of atoms of each element present in a molecule of the compound]
A. 14g/mol x 8 112g/mol (14g/mol is found by adding together the elements Moler mass)
CH2 –> C8H16 112 / 14 = 8
1 x 8 = 8 2 x 8 = 16
100-92.3=7.7%
H C
7.7% 92.3
/ 1 / 12
= 7.7 = 7.7
= 1 = 1 CH (13g/mol)(13 x 6) –> C6H6 (78) (78/13 = 6)
What is water crystallisation? what does anhydrous mean?
crystals of some ionic salts contain water loosely bonded to the ions in the crystal lattice. when is crystal is heated it becomes anhydrous which means it does not contain water of crystallisation.
