2.1 Flashcards
relative charge of proton
1+
actual: +1.60217733 x 10-19
relative charge of neutron
0
relative charge of electron
- 1
actual: -1.60217733 x 10-19
relative mass of proton
1
relative mass of electron
1/1836
relative mass of neutron
1
actual: measurements shows neutron has slightly greater mass than proton but number is close to 1 so scientists assume protons and neutrons have the same mass
where is most of the mass of the atom located?
in the nucleus
what is the overall charge of an atom
zero, the atom is neutral as positive charge from protons is cancelled out by negative charge of electrons
Why are neutrons considered to be the glue of the atom?
holds nucleus together despite the electrostatic repulsion between protons
an atom will contain same number, if not slightly more, neutrons than protons
as nucleus gets larger, more neutrons are needed
how is the periodic table arranged?
in order of increasing atomic number
atomic number
The atomic number (proton number) of a chemical element is the number of protons found in the nucleus of every atom of that element. (so every atom of the same element has the same number of protons and different elements contain atoms with different number of protons)
It is identical to the charge number of the nucleus
isotope definiton
isotopes are atoms of the same element with different number of neutrons and different masses
mass number
the total number of protons and neutrons in an atom
e.g O 16
atomic number
number of protons in an atom e.g O 8
isotope notation A
A = protons + neutrons
isotope notation Z
Z = number of protons
how would you find the number of neutrons
mass number - atomic number
Why do different isotopes of the same element react in the same way?
chemical reactions involve electrons of an atom
different isotopes of the same element have the same number of electrons
the number of neutrons has no effect on the reaction
do isotopes have physical and chemical differences?
NO chemical - react in same way as same no of electrons
YES physical - e.g boiling points, melting points, density
ion definition
an ion is a charged particle as a result of losing or gaining an electron
what are anions
anions are negative ions, atoms with more electrons than protons and therefore have a negative overall charge
what are cations
cations are positive ions, atoms with less electrons than protons and therefore have a positive overall charge
