2. ATOMS, IONS, AND COMPOUNDS Flashcards
Define Isotope
Atoms of the same element with different numbers of neutrons and different masses
Define Relative isotopic mass
The mass of an isotope compared with 1/12th mass of carbon-12
Define Relative atomic mass
The weighted mean mass compared with 1/12th mass of carbon-12
What is a Shell?
A group of atomic orbitals with the same principle quantum number, n
What is the Atomic number?
The number of protons in the nucleus of an atom
What is the Mass number?
The sum of the number of protons and neutrons in the nucleus
What is an Ion?
A positively or negatively charged atom or group of atoms
What is a Cation?
A positively charged ion
What is an Anion?
A negatively charged ion
What is a Binary compound?
A compound containing two elements only
What is a Polyatomic ion?
An ion containing more than one atom
What is a Diatomic molecule?
A molecule containing two atoms bonded together
Write down everything you know about Atomic structure and isotopes
(6)
Proton, p+
-> 1+ charge, mass of 1
Electron, e-
-> 1- charge, mass of 1/1836
Neutron, n
-> 0 charge, mass of 1
The number of protons in an atom identifies the element, every atom of the same element contains the same number of protons
Isotope = Atoms of the same element with different numbers of neutrons and different masses
Different isotopes of the same element have the same number of electrons -> The number of neutrons has no effect on reactions of an element -> Different isotopes of an element therefore react in the same way.
-> There may be small differences in physical properties - higher mass isotopes having higher melting and boiling points and densities
Ion = a charge atom
A cation is a positive ion
An anion is a negative ion
Write down everything you know about Relative mass
(6)
The strong nuclear force holding together protons and neutrons comes at the expense of the loss of a fraction of their mass
-> This small amount of mass lost is called the mass defect
Relative isotopic mass = The mass of an isotope compared with 1/12th of the mass of carbon-12
Relative atomic mass = The weighted mean mass compared with 1/12th of the mass of carbon-12
The weighted mean mass takes account of:
- The percentage abundance of each isotope
- The relative isotopic mass of each isotope
Mass spectrometer is used in the determination of relative isotopic masses and relative abundances of the isotope.
Mass-to-charge ratio m/z = relative mass of ion / relative charge of ion
Percentage abundance on y-axis, m/z on x-axis
The term Relative molecular mass is used for simple molecules
The term Relative formula mass is used for compounds with giant structures
Write down the Diatomic molecules you need to remember
H2
N2
O2
F2
Br2
I2
P4
S8
