Chemistry (Atomic Structure and Bonding) Flashcards
Ionic Bonding
Type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound. Such a bond forms when the valence (outermost) electrons of one atom are transferred permanently to another atom.
How do ionic bonds form?
An ionic bond is formed when a metal atom interacts with a non-metal atom. The metal atom is of low electronegativity and needs to lose electrons to become stable with a full outer shell. The non-metal atom is of high electronegativity and needs to gain electrons to become stable with a full outer shell.
What happens when a metal atom is near a non-metal atom?
(hint: Charges of ions?)
The metal atom, having lost electrons (which are negative) becomes a positively charged ion (cation)
The non-metal atom, having gained electrons, becomes a negatively charged ion (anion).
The positive ion forms an electrostatic attraction to the negative ion and an ionic bond is then formed.
Physical Properties of Ionic Bonds
Hard and Brittle
High melting and boiling points
Solids at room temperature
Can conduct electricity in solution or as a liquid but not as a solid
Soluble in water but not in solvents such as petroleum
What are monatomic and polyatomic ions? (& examples)
Monatomic ions are ions that have one atom (e.g. silver (Ag+), magnesium (Mg2+), Aluminium (Al3+), and chloride (Cl-).
Polyatomic ions are ions with multiple atoms. (e.g. ammonium (NH4+), nitrate (NO3-), carbonate (CO32-), phosphate (PO43-) and sulfate (SO42-)).
What is the general formula for writing ions?
- Monatomic cations are named after the metal they come from.
- Monatomic anions are names after the non-metal they came from but the end is changed to “ide”. For example, Cl- is chloride, S2- is sulfide and N3- is nitride.
- A polyatomic anion which is saturated with oxygen is given the ending “ate”. e.g. (CO3)
- If the polyatomic anion has a hydrogen in front of it, then the word “hydrogen” is written in front of it. For example, carbonate (CO32-) becomes hydrogencarbonate (HCO3-).
What is the chemical structure of a metallic bond?
Consists of positive ions arranged in a lattice formation with the valence electrons flowing between them. The electrons are delocalised, which means they are able to flow freely between the metal ions. As the ions are positive and the electrons are negative, there is a strong electrostatic attraction that can hold the metal together.
What is a Covalent Bond?
A covalent bond occurs between non-metallic atoms that have a large number of valence electrons and only need a few to fill their shell. The atoms interact to share electrons, which cause them to form molecules.
What are the types of covalent bonds? What requirements are needed to meet them? What about Carbon and Silicon Bonds?
- Single: If the two non-metal atoms that are interacting each need one electron to fill their valence shell.
- Double: If the two non-metal atoms that are interacting each need two electrons to fill their valence shell.
- Triple: If the two non-metal atoms that are interacting each need three electrons to fill their valence shell.
Carbon and silicon atoms have four valence electrons in their valence shell and can form single, double and triple bonds with other substances.
Properties of Covalent Bonds
*Non-conductors of electricity: all of the electrons in a covalent bond are fixed in place and are not free to carry an electric charge.
*Low melting and boiling points: Although the covalent bonds are extremely strong, the intermolecular forces between molecules are weak which means that it doesn’t take much heat to break them apart.
*They are usually liquids or gases at room temperature: See the reasoning above.
*Solids are soft and easy to mould: See the reasoning above.
*Only polar molecules are soluble in water: If there is a separation in charge within a molecule, it can be dissolved in water.
Covalent Network Compounds
A covalent network compound is a substance that is made up of a large network of covalently bonded atoms, held together by intermolecular forces.
Difference between Covalent Network and Covalent bonded compounds
The difference between a covalent network compound and a large covalent molecular compound is that the network solely comprises of repeating units whereas a molecule has variations in its structure. Also covalent network compounds have intermolecular forces holding them together, whilst covalent molecules are held together purely by covalent bonds.
What is an Allotrope?
Allotropes are different structural forms of the same element that gives it different physical properties. For example, graphite and diamond are allotropes of each other as they solely consist of covalently bonded carbon atoms.
Properties of covalent network compounds
- Non-conductors of electricity
- Very hard
- Solids at room temperature
- Insoluble in everything
Properties of Metallic Bonds?
Shiny
Hard
High melting and boiling points
Conduct electricity
Conduct heat
Malleable and ductile
