Atomic Structure Flashcards
(23 cards)
Where is most of the mass concentrated in an atom?
The nucleus
What is a nucleus?
A very small, dense centre of the atom
What are the shells?
Energy levels surrounding the nucleus where there is a high probability of finding an electron.
What is the relative mass and the relative charge of a proton?
1
+1
What is the relative mass and the relative charge of a neutron?
1
0
What is the relative mass and the relative charge of an electron?
1/1836
-1
What is the definition of atomic number?
Atomic number is the number of protons in the nucleus of an atom of an element.
What is the definition of mass number?
Mass number is the SUM of protons PLUS neutrons in the nucleus of an atom of an element.
What is an isotope?
Isotopes are different atoms of the same element with the same number of protons and DIFFERENT number of neutrons in their nuclei.
What is the definition of relative atomic mass?
RAM is the weighted average mass of an atom of an element relative to to the mass of an atom of carbon- 12 which has a value of 12,000
How do you calculate the ram?
Eg. Solve ( with working )
- 37
Cl. : Cl - 17
75%. : 25%
In 100 atoms...
RAM= 75x35 + 25x37
-----------------
100
= 3550
--------
100
= 35.5
What is the relative formula mass?
The sum of the ram is of the atoms in the formula
Working out RFM…..
Try…. H20, NH3, AL(NO3)3
H20
2x1 + 16 = 18
NH3
14 + ( 16 x 2 ) = 17
AL(NO3)3
27 + ( 14 x 3 ) + ( 16 x 9 ) = 213
How do you work out the percentage composition by mass?
Percentage by mass =
Total mass of compound
x 100
What is the definition of a mole?
A mole is that amount of substance containing the same number of particles as there are atoms of carbon-12 in 12 g of carbon
What is the number of a Mole?
6.02×10^23
What is a mole also known as?
AVOGADRO’ S NUMBER
When working out the mole and the mass for an element what is the rule?
1 mol of atoms of any element has a mass = ( relative atomic mass )
When working out the mole and the mass for a compound what is the rule?
1 mol of a compound has a mass = ( relative formula mass )
What is an atom made up of?
Protons, neutrons, electrons
What is the periodic table?
The periodic table is an arrangement of elements in order of increasing atomic number
What does the group number equals?
Group number equals the number of electrons in the outer shell
What does the period number equal?
The period number equals the number of occupied shells
