Chapter 1 Structure and Bonding Flashcards
What is an atom
an atom consists of a dense, positively charged nucleus surrounded at a relatively large distance by negatively charged electrons.
What is a nucleus
Nucleus consists of subatomic particles called neutrons, which are electrically neutral, and protons, which are positively charged.
Atomic Number (Z)
Gives the number of protons or an atom contains.
Mass number (A)
which gives the total number of protons and neutrons in its nucleus.
Isotopes
Atoms with the same atomic number but different mass numbers are called? Neutrons can change.
Atomic Weight
The weighted-average of an element’s naturally occurring isotopes is called…..
Node
A region of zero electron density around the nucleus.
Atomic Orbital
A mathematically defined 3D region of space around a nucleus where an electron spends its time.
Electron Cloud
made from electrons relatively small and contain 1- charge, determines volume of an atom.
Electron shell
The orbitals in an atom are organized into different layers around the nucleus called….
Aufbau principle
The lowest-energy orbitals fill up first, 1S->2S->2P->3S
Pauli exclusion principle
Only two electrons can occupy an orbital, and they must have opposite spins.
Hund’s Rule
If two or more empty orbitals of equal energy are available, one electron occupies each with spins parallel until all orbitals are half-full.
Covalent bond
shared electron bond not by gaining or losing electrons, but by sharing them.
Molecule
The neutral collection of atoms held together by covalent bonds.