Module 2 - Atomic Structure and Isotopes , Compounds, formulae and equation Flashcards
What is the charge of a
proton?
1+
What is the charge an
electron?
1-
Which particle has the same
mass as proton?
Neutron
Which two particles make up
most of atom’s mass?
Protons and neutrons
Which letter is used to
represent the atomic number
of an atom?
Z
What does the atomic number
tell about an element?
Atomic number = number of protons in
an atom
Which letter represents the
mass number?
A
How is mass number
calculated?
Mass number = number of protons +
number of neutrons
How to calculate the number
of neutrons?
Number of neutrons = mass number -
atomic number
Define isotope
Atoms of the same element with different
number of neutrons
Why does different isotopes of
the same element react in the
same way? (2)
● Neutrons have no impact on the chemical
reactivity
● Reactions involve electrons, isotopes have
the same number of electrons in the same
arrangement
What are ions?
Charged particles that is formed when an
atom loses or gains electrons
What is the charge of the ion
when electrons are gained?
Negative
N.B - positive charge when electrons are lost
E.g. 3+ ion has lost 3 electrons
What is the unit used to
measure atomic masses
called?
Unified atomic mass unit, u
Define relative atomic mass
The weighted mean mass of an atom of
an element compared with one twelfth of
the mass of an atom of carbon -12
What is the unit of relative
atomic mass?
No units
Define relative isotopic mass
The mass of an atom of an isotope
compared with one twelfth of the mass of
an atom of carbon-12
The relative isotopic mass is
same as which number?
Mass number
What two assumptions are
made when calculating mass
number?
- Contribution of the electron is neglected
- Mass of both proton and neutron is taken
as 1.0 u
How to calculate the relative
molecular mass and relative
formula mass?
Both can be calculated by adding the
relative atomic masses of each of the
atom making up the molecule or the
formula
What are the uses of mass
spectrometry? (3)
● Identify unknown compounds
● Find relative abundance of each isotope of an
element
● Determine structural information
How does a mass
spectrometer work?
● The sample is made into positive ions.
● They pass through the apparatus and are
separated according to mass to charge ratio.
● A computer analyses the data and produces
mass spectrum.
How is the group number
related to the number of
electrons?
Group number = number of electrons in
the outer shell
Does the group number
indicates horizontal or vertical
column in the periodic table?
Vertical column
Do metals usually gain or lose
electrons?
Lose electrons
Which are the 4 elements that
don’t tend to form ions and
why?
The elements are beryllium, boron, carbon
and silicon
Requires a lot of energy to transfer outer shell
electrons
What are molecular ions?
Covalently bonded atoms that lose or
gain electrons
What is the charge of an
ammonium ion?
+1 → NH4+
What is the charge of a
hydroxide ion?
-1 → OH-
What is the charge of a nitrate
ion?
-1 → NO3-
What is the charge of a
carbonate ion?
-2 → CO3^2-
What is the charge of a sulfate
ion?
-2 → SO4^2-
What is an empirical formula?
Simplest whole number ratio of atoms of
each element present in a compound
How to calculate empirical
formula?
● Divide the amount of each element by its molar
mass
● Divide the answers by the smallest value obtained
● If there is a decimal, divide by a suitable number
to make it into a whole number
