Chemical Bonding Flashcards
What is a coumpound
A substance that is made up of two or more different elements combined together chemically
What is the octet rule
When bonding occours, atoms tend to reach an electron arrangement with eight electrons in the outermost shell
What are expections to the Octet rule
Transition elements dont obey the octet rule and often have more or less than 8 electrons in the outer shell
Elements near helium tens to have 2 electrons in the outer shell
What is an ion
A charged atom/ group of atoms
What is a postive ion called
Cations
What is a negative ion called
Anions
What is an ionic bond
The force of attraction between oppositly charged ions in a compound
What do you use to show the formation of ionic bonding
Bohr diagrams, dot and cross diagrams
What structure do ionic compounds have
Crystal lattice structure
What are crustal lattice structures dertimined by?
X-ray crystallography
Charateristics of ionic compounds
Hardness- hard substances due to strong ionic bonds and crystal lattice structures.
Melting and boiling points- high melting and boiling points due to strong ionic bonds and crystal lattice structure.
Conduction of electricity.Dont condict electricity in solid state but do conduct electricity in the molten state or when dissolved in water as the ions are free to carry the charge.
What are elements placed in the transition metal block but not transition elements, and why are they an expection?
Sc and Zn are not transition metals.Sc and Zinc have different properties to the other transition elements
what is a transition metal
An elements that forms at least one ion with a partially filled d sublevel.
What are the properties of transition elements
Transition elements have varaible valency. Sc only forms SC3+ ions and zn only forms Zn 2+ ions
transition elements usually form colourful compounds, scandium and zinc only form white compounds.
Transition elements are widely used as catalysts. Sc and zn show little catalytic activity.
varable valency
the number of atoms of different elements in which a certain element can combine with.
What is a covalent bond
One which involves that sharing of electrons between atoms.
What is a molecule
Agroup of atoms joined together. Its the smallest partical of an element or compound that can exist independently
What can molecules only be used for
Covalent compounds
What is the Valency of a element
The number of atoms of hydrogen or any other monovalent element with which each atom of the element combines
What is a single bond
one pair of electrons are shared between two atoms
What is a double bond
two pairs of electrons are shared between two atoms
What is a triple bond
three shared pairs of electrons
what is a group of organic compounds called
Aldehydes
What is a sigma bond
A sigma bond is fored due the head-on overlap of two orbitals
(All single covalent bonds can be describes as a sigma bond)
What is formed when two atomic orbitals overlap
Molecular orbital
What is a pi bonf
A pi bond is formed due to sideways/ lateral overlap of P orbitals
Are Sigma bonds stronger or Pi bonds stronger
There is less overlap between orbitals in a pi bond, therefore it is weaker than a sigma bond
What does a single covalent bond consist of
1 sigma bond
What does a double covalent bond consist of
1 sigma and 1 pi bond
What does a triple covalent bond consist of
1 sigma and two pi