atomic structure and the periodic table Flashcards
what are isotopes?
atoms of the same element that have a different number of neutrons
what is an example of an isotope
chloride 35 and chloride 17
what are the characteristics of chloride 35
18 neutrons
17 protons
17 electrons
abundance 75%
what are the characteristics of chloride 37
20 neutrons
17 protons
17 electrons
abundance 25%
why is the chloride on the periodic table called chloride 35.5 and not chloride 36?
the relative atomic mass is the average value for the isotopes of an element therefore
75% x 35 + 25% x 37 = 35.5
(abundance x atomic mass)
The atomic charge of of protons,neutrons and electrons (numbers)
Protons = +1 Neutron = 0 Electrons = -1
The atomic mass of protons,neutrons and electrons
Protons = 1 Neutrons = 1 Electrons = 1/2000 or negligible
what is found in the nucleus of an atom
protons and neutrons
what is found in the shells of an atom
electrons
what charge do protons,electrons and neutrons have
protons = positive electrons = negative neutron = neutral
why is an atom neutral?
Atoms are neutral because they have equal numbers of positive protons and negative electron.
what is the mass number
number of protons and neutrons
what is the atomic number
number of protons
how do you calculate the number of neutrons?
mass number - atomic number
what are the elements on the left side of the periodic table called?
alkali metals
what are the elements on the right side of the periodic table called
non metals (have intermidiate chemical properties)
what is the special name for group 7 elements
halogens
what is the special name for group 8 / 0
noble gases
what is the ‘staircase’ on the right side of the periodic table called
metaloids / semi metals
what are they called semi metals?
Because they have properties of both metals and non metals
what are the elements in the middle called
transition metals
How are the metals arranged
In increasing atomic order
Groups are …
periods are …
vertical
horizontal
what do elements in the same group have in common?
Elements in the same group have similar properties e.g group 1 and group 7 because they have the same number of electrons in the outer shell
what can the last number in an electric configuration tell you
Number of electrons in the outer shell is the group number
what can all the numbers in an electric configuration tell you
Number of shells is the period number
what is a chemical reaction
The loss or gain of electrons
what is an ion
An atom that has loss or gained electrons
Metals always …
metals always LOSE electrons to form POSITIVE ions
None metals always ….
Non metals always GAIN electrons to form NEGATIVE ions
what does the electronic configuration become of an ion?
e. g 2.8.1 to 2.8 for metals
e. g 2.8.7 to 2.8.8 for non metals
how do you write an atom as an ion?
put brackets around it and add the charge
what is the ionic symbol of a metal
+
what is the ionic symbol of a non metal
_