1.2 Inside the atom Flashcards
Every atom has nearly all of its mass
concentrated in a tiny region in the center of the atom called nucleus
The nucleus is made up of particles called
nucleons (protons+neutrons)
Atoms of the same element have
the same number of proton
Where are electrons found in an atom?
Outside the nucleus in a region of space called the orbitals
Chemists often find it convenient to use a simpler model in which
electrons move around the nucleus in electron shells
In an orbital model, each shell is a certain distance away from the nucleus at its own particular
energy level
We use the orbital model to
discuss where electrons really are in space
In an orbital model, there is a probability of finding
a particular electron within a certain area of the space outside the nucleus
When do we use the orbital model?
When are discussing bonding and referring to electrons in the sub shells
The values of the charges are too small to be useful when discussing
general chemical properties
How is the problem of the values of charges and
masses being too small when discussing general chemical properties solved?
By comparing their masses and charges using general their relative charges and masses
What are relative charges and masses of the subatomic particles
These are the charges and masses of the subatomic particles compared with each other in a simple ratio.
Relative mass of an electron
1/1836
Relative mass of a neutron
1
Relative mass of a proton
1
Relative charge of an electron
-1
Relative charge of a neutron
0
Relative charge of a proton
+1
What is the atomic number/proton number?
It is the number of protons in the nucleus of the atom
What is the symbol for atomic number
Z
In what order is the periodic table arranged?
In order of the atomic numbers
What is the mass number/nucleon number?
It is the number of protons plus neutrons in the nucleus of an atom
What is the symbol of mass number?
A
Define Isotopes
Atoms of the same element with different mass numbers
Why do isotopes of a particular element have the same chemical properties?
They have the same number of electrons.
Why do isotopes of a particular element have slightly different physical properties?
They have different number of neutrons which causes a small difference in mass as well as density.
Two types of isotopes
Radioactive and non radioactive isotopes
Radioactive isotopes are also known as
Radioisotopes
What are two industrial uses of radioisotopes
Check for leaks in oil/gas pipelines and to check the thickness of the paper
What are two medical uses of radioisotopes?
Treat some types of cancer and check the activity of thyroid gland in the throat
What are ions?
They are charged particles made by the loss or gain of electrons from an atom or group of covalently bonded atoms.
The positive ions are formed when
one or more electrons are lost by an atom
The negative ions are formed when
one or more electrons are gainedby an atom
