Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
10 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
What is ionic bonding? |
Ionic bonding occurs between positive and negative ions, which attract each other and bind together to form ionic compounds. For example, sodium chloride consists of Na+ ions and Cl- ions bound together. Each ion is surrounded by oppositely charged ions held in place by electrostatic attraction and forming an ionic crystal lattice. The ions in a crystal lattice are very strong bonded - a high temperature is required to melt the crystal. |
What does it occur between? What temperature is required to melt a crystal? |
|
|
Different ways in which atoms chemically combine together to make compounds |
One of these ways is called ionic bonding. Atoms turn into ions when they lose or gain electrons. I will be explain this further later. |
How do atoms turn into ions? |
|
|
Metal ions |
In some circumstances metal atoms may lose electrons. The atom then has more protons than electrons and so it will be positively charged, a positive ion. |
Do metal atoms gain/ lose electrons? Will it be negatively charged/ positive? |
|
|
Non-metal ions |
Non metal atoms may gain electrons and become negatively charged. Example: An oxygen atom may gain two electrons and become an O2- ion. |
Do non-metal atoms lose/ gain electrons? Can you give an example? |
|
|
More on ionic bonding |
Positive and negative ions attract one another and bind together forming a new substance. The is called ionic bonding. For example: Sodium chloride consists of Na+ and Cl- ions bound together. Magnesium oxide consists of Mg2+ ions and O2- ions bound together. Ionic compounds like magnesium oxide and sodium chloride have high melting points and do not conduct electricity when solid. They do conduct electricity when molten. Sodium chloride is soluble in water and the solution conducts electricity. |
How are new substances formed? Can you give an example? |
|
|
Dot and cross model - higher tier only |
The formation of ionic compounds is often shown with dot and cross models. For example, a sodium atom loses one electron from its outer shell to become a possitively charged sodium ion. It can be represented in a diagram like this: |
|
|
|
However… |
On the other hand an oxygen atom gains two electrons in its outer shell to become a negatively charged oxygen ion: notice how atoms gain or lose just the right number of electrons to produce an ion with a complete outer shell of electrons. This is sometimes called a stable octet. The positive and negative ions attract each other and form an ionic bond. We can draw this using dots for one atom and crosses for another atom. This is called a dot and cross diagram. |
How does an oxygen atom become a negatively charged ion? What is a stable octet? |
|
|
Example using dot and cross diagram |
Nsns |
|
|
|
Ionic lattice |
Each ion is surrounded by oppositely charged ions held in place by electrostatic attraction and forming an ionic crystal lattice. The number of ions in an ionic compound is such that the overall charge of a sample of the compound is zero. |
|
|
|
Ionic lattice example |
Example: Magnesium chloride consists pf Mg2+ and Cl- ions. Twice as many chloride ions as magnesium ions are needed to make the substance neutral. The formula of magnesium chloride is MgCl2. The ions in a crystal lattice are very strongly bonded together so a high temperature is required to separate the particles and melt the crystal. The ions are held strongly in position so they cannot move and carry an electric current. If an ionic compound is melted or dissolved in water the ions are then free to move and so the substance can be electrolysed. |
|
