Chapter 4: Chemical Bonding And Structure Flashcards
(183 cards)
What bond is present in inert gases
Weak force of attraction
What does a bond mean
Binding force
What is a chemical bond
Force of attraction between particles
Different ways in which particleS bond and the result of each
•small or large numbers •similar or different atoms
Result of combination is a stable association called a chemical bond
How do bonded atoms differ from parent atoms
They have very different properties
Why are bonds formed
To achieve a more stable outer electronic configuration of 2 OR 8 electrons . This is the Octet rule
How can bonds form foe stable configuration
Losing, gaining, sharing, or freeing electrons in the outer shell
State the general number of electrons in metals outer shells and how they attain a stable atom
Small valance no. (1,2,3)
Lose electrons to form postive ions called cations
State the general number of electrons in nonmetals outer shells and how they attain a stable atom
Higher valance nos. (5,6,7)
Gain electrons to form negative ions called anions
What is the bonding tendency of group 4 elements and why
Do not gain or lose electrons so don’t form ions. Because the energy involved to transfer electrons is too large to be favourable. They react to form a different type of bond
What is the ionic bond model
- electrostatic force between ions which are small, spherical, charged particles attracting eachother
- electrons are transferred completely from on outer shell to another atom’s so do not physically affect electrons of each other
- total charge for a formula unit of ionic substance is 0
What is an ionic bond
Electrostatic force of attraction between positive and negative ions
State the structure of ionic compounds
- giant ionic lattice
- lattice is an orderly arrangement of particles in a 3d space
- the lattice is made of postive and negative ions arranged at regular distances beside each other continuously throughout the solid
- crystals are solids with plane surfaces arranged att regular angles to each other
Describe the structure of NaCl lattice from memory
Chlorine- ions are relatively larger than Sodium+ ions
Each chlorine ion is surrounded by 6 sodium ions
Imagine that ^
What are 3 properties of ionic compounds and explain each
- high melting and boiling points due to strong electrostatic force between oppositely charged ions
- conduct electricity when molten or aqueous but not in solid state, because ions are free to move only when molten or dissolved in water
- brittle and cleave (spilt as cut) along planes because ions of same charge come closer as crystal planes slide over each other so they repel strongly
- soluble in polar (water) solvents but not in organic ones (benzene)
Describe how ionic compounds dissolve in water
Water is polar. It has a separation of charge though partial. At contact surface molecules are attracted to ions of opp charge in the lattice which may cause ions to dislodge from their positions and become surrounded by molecules are said to hydrated and hence dissolves
State the equation for NaCl dissolving
NaCl(s)+H2O–>NaCl(aq)
NaCl(s)+H2O–>Na+(aq) + Cl-(aq)
When is a liquid, other than water, can dissolve an ionic substance the solid is said to be
Solvated
Why are non polar substjaces not able to dissolve ionic solids
No charge separation. No attraction between liqued and ions so ions remain tightly bound to eachother
Solubility trends are based on
Similar chemical nature of solute and solvent to most likely lead to successful interactions
“Like dissolves like”
Why do elements covalently bond
When the ionization energies to obtain an inert gas configuration are very high, so much that a single ion of these elements becomes unstable
How is covalent bonding done
Non metal atoms share electrons so each atom has a stable configuration in the outer shell
The shared electrons are concentrated between and simultaneously attracted by both nuclei so they can contribute to each atoms structure.
This is only possible if electrons are strongly localised between atoms
What is a covalent bond
Electrostatic force of attraction between shared electrons and positive nuclei of the two atoms
A molecule is
Group of atoms held together by covalent bonds