Bonding Flashcards
Why do elements form compounds and bonds? How?
Elements react with each other (to create bonds and compounds) to complete their outer shells and achieve the stable electronic structure of a noble gas: usually having 8 electrons in its outer shell.
Why are noble gases unreactive?
Noble gases already have full outer shells - meaning that they are already stable and have no incentive to react and form bonds.
What is the definition of an atom?
The smallest particle of an element that can exist on its own yet still be recognised as that element.
What is the definition of an ion?
An electrically charged particle formed when an atom gains or loses an electron or electrons.
What is the definition of a cation?
A positively charged ion formed when an atom loses an electron or electrons.
What is the definition of an anion?
A negatively charged ion formed when an atom gains an electron or electrons.
What is a molecule?
A particle made from two or more atoms covalently bonded.
What is a molecular ion?
A charged particle containing more than one atom.
What is ionic bonding?
Ionic compounds are formed between metal and non-metal elements. This involves transferring electrons from a metal atom to non-metal atom producing positive metal ions and negative non-metal ions. In this way the ions formed have a complete outer shell of electrons, a stable noble gas type arrangement.
What types of metals and non-metals generally form ionic bonds?
Give an example.
Ionic compounds are often formed between Group I or Group II metals and Group VI or VII non-metals.
For example - Sodium (2,8,1) and chlorine (2,8,7) react to form the ionic compound sodium chloride (2,8,8) which has a full outer shell of electrons.
Why do ionic bonds stick together? How strong is the bond?
The metal ion (which has a negative charge) is unlike in charge to the non-metal ion (which has a positive charge) - since unlike charges attract the ions bonds together to form a strong bond. The electrostatic attraction between the ions is strong.
Draw the electronic structure of Ca and Cl and how they form CaCl₂.
Describe the reaction.
Each calcium atom transfers one electron to each of the two chlorine atoms. Calcium chloride has twice the number of Cl- ions than Ca 2+ ions, so the formula is CaCl₂.
What is covalent bonding?
This type of bonding involves sharing pairs of electrons between non-metal atoms. In compounds formed between non-metals, both atoms need to gain electrons to achieve a noble gas type electrons structure. They do this by sharing electrons.
Draw the dot and cross diagram for the covalent bond in Hydrogen, H₂.
Each hydrogen atom has one proton and one electron. For a complete electron shell each hydrogen atom needs one more electron. It achieves this by sharing a pair of electrons with another H atom.
The two H atoms bond together to form a molecule. There is a strong attractive force between the two positive nuclei and the shared pair of electrons.
What does diatomic mean? Give an example.
To stay stable, the atom of an element form a covalent bond between another atom (of the same element).
For example oxygen atoms travel in pairs to stay stable and have a full outer shell because of this. Atoms travelling in pair (of the same atom) are diatomic.
Draw the dot and cross diagram for the covalent bond for Oxygen, O₂
One oxygen atom has a 2,6 electronic structure - meaning that it needs to share another two electrons. So oxygen atoms link up together forming O₂ - since the two oxygen atoms are sharing a bond consisting of two electrons it is called a double bond.
Draw the dot and cross diagram for the covalent bond for Nitrogen ,N₂
Nitrogen has only 5 electrons in its outer shell, so it needs to share three more electrons with another nitrogen atoms. Nitrogen is diatomic because it exists as a diatomic molecule.
Since Nitrogen is sharing three electrons it forms a triple covalent bond.
Draw the covalent bond for Hydrogen chloride.
Draw the covalent bond for water. What is its formula?
Formula = H₂O
Draw the covalent bond for Ammonia. What is its formula?
Formula - NH₃
Draw the covalent bond for methane. What is its formula?
Formula = CH₄
Draw the covalent bond for Carbon Dioxide. What is its formula?
Formula = CO₂
Order the different types of covalent bonds for strongest to weakest. Why?
All covalent bonds are strong, however, the strongest goes as following: Triple covalent bond, Double covalent bond and Single covalent bond.
All covalent bonds are strong but the more pairs of electrons that are shared between two atoms the stronger their positive nuclei will be attracted to the shared electrons and thus the stronger the bonds.
How does bond lengths change from single to double to triple covalent bonds?
Longest goes as following:
Single covalent bond (longest)
Double covalent bond
Triple covalent bond (Shortest)
What is metallic bonding?
In metals the atoms are packed closely together in a regular pattern: a regular lattice. When bonding the outer electrons of the metal atoms are lost (forming free electrons which move throughout the lattice) and a regular lattice of positive ions are left behind. The positive ions are attracted to the free electrons and are thus held together.
The positive metal ions in a regular arrangement are attracted and held together in a sea of delocalised electrons (forming a lattice).
Summarise metallic bonding? How can you remember this summary?
PIRASE:
Positive metal
Ions in a
Regular arrangement
Attracted
Sea of delocalised
Electrons
