Structure 2.4 Flashcards
What happens when there is zero/very low electronegativity difference?
bonds are non-polar
What happens when there is medium electronegativity difference?
increasing ionic character or molecules are polar
low average electronegativity - ionic
medium to high - polar covalent
What happens when there is high electronegativity difference?
substance is ionic, polar bonds
What do the edges of the bonding triangle represent?
bond types of substances that fall somewhere between two bond types
What is the difference between ionic/polar covalent/non polar covalent bonding?
ionic - transfer of electrons
polar covalent - electrons shared unequally
nonpolar covalent - electrons shared equally
Wher is polar covalent in the bonding triangle?
between ionic and covalent
What is bonding best described as?
a continuum between the ionic, covalent and metallic models rather than discrete categories
What are the y and x axis in the bonding triangle?
y axis - electronegativity difference
x axis - average electronegativity
What are the traits of substances along a boundary line?
show intermediate bonding and properties
Why is SiO2 a good example of a substance along the boundary of the triangle?
network covalent structure
brittle, high melting point, but still has covalent bonds
What are alloys?
mixtures of a metal and other metals/non-metals, usually with a base metal
results in different properties than the base metal
What are the two main types of alloys?
substitutional - element added replaces the metal ions
interstitial - element added occupies vacant space in the lattice
How is the bonding in alloys?
non directional, electrostatic force still occurs in all directions
not structurally arranged in a fixed ratio
How are alloys different in properties from the base metal?
- less malleable, harder: different sizes prevent layers from sliding over each other
- often lower melting points: weaker metallic bonds due to varying cation size
