Topic 2b - Bonding (Year 10) Flashcards
What does an ionic bond form between?
metal and non-metal
What does a covaltent bond form between?
non-metal and non-metal
What does a metallic bond form between?
metal and metal
How does an ionic bond form?
The metal loses electrons to become a positively charged ion, the non-metal gains electrons to become a negatively charged ion
How does a covalent bond form?
non-metals share pairs of electrons to gain full outer shells
How does a metallic bond form?
Metals lose their outer shell elctrons into a sea of delocalised electrons
If an atom loses two electrons to form an ion, what charge will the ion have?
+2
If an atom gains two electrons to form an ion, what charge will the ion have?
-2
Elements in group 1 will form ions with what charge?
+1
Elements in group 2 will form ions with what charge?
+2
Elements in group 3 will form ions with what charge?
+3
Elements in group 4 will form ions with what charge?
Group 4 don’t form ions because it is just as hard to lose 4 electrons, as it is to gain 4 electrons. Group 4 elements take part in covalent bonding.
Elements in group 5 will form ions with what charge?
-3
Elements in group 6 will form ions with what charge?
-2
Elements in group 7 will form ions with what charge?
-1
Elements in group 0 will form ions with what charge?
Group 0 don’t form ions because they already have a full outer shell
When are elements stable?
When they have a full outer shell of electrons
In ionic bonding, how are ions held together?
Electrostatic forces of attraction
Zinc Hydroxide is made up of Zn2+ ions and OH- ions. What is its formula?
Zn(OH)2
Sodium carbonate is made up from Na- and CO32-. What is its formula?
Na2CO3
Explain how Calcium Oxide forms. Remember Calcium is in gorup 2 and Oxygen is in group 6
Calcium loses 2 electrons becoming a 2+ ion and Oxygen gains 2 electrons becoming a 2- ion
Do ionic compounds have high or low melting points?
Ionic compounds have high melting points
Why do ionic compounds have high melting points?
Ions are held together by strong electrostatic forces of attraction
Give a limitation to the ball and stick models to represent ionic compounds
The model isn’t to scale. It shoes gaps between ions.
How are ions arranged in an ionic compound?
Giant ionic lattice
Can ionic compounds conduct electricity?
Yes but only when molten or dissolved in water
Why can ionic bonds only conduct electricity when molten or in a solution?
When solid, the ions in an ionic compounds can’t move. When molten or in solution th ions are free to move
Define the term: dissociate
To separate into separate ions. We talk about dissociation in terms of ions in ionic compounds dissociating when in a solution
Explain why carbon forms covalent bonds with 4 hydrogen atoms in CH4
Carbon has 4 electrons in its outer shell, so need for 4 covalent bonds to gain a full outer shell. Hydrogen has 1 electron in its outer shell and needs to form one single bond to gain a full outer shell. So you need 4 hydrogen atoms for each 1 carbon atom
Poly(ethene) is a polymer. Describe the structure of a polymer
A polymer is made up from a long chain of covalently bonded carbon atoms
True or False: All simple covalent molecular substances are insoluble in water
False, Some simple molecular substances are soluble and some are insoluble
True or False: O2 has a double bond
True, Oxygens structure is O=O
Is a covalent bond strong?
A single covalent bond is very strong. It is extremely hard to try and bbreak a bond where they are sharing electrons.
Why don’t simple molecular substances conduct electricity?
There is no charged ions and there is no free electrons that can move to carry electricity
Why do simple molecular substances have low melting and boiling points?
Simple molecular substances have low melting and boiling points because there was weak intermolecular force of attraction between moleculs that can easily be broken.
H2 and CH4 are both covalent compounds. Which would have the highest boiling point?
CH4 would have the highest boiling point. The larger the molecule the stonger the intermolecular forces, meaning the more energy needed to break them.
Define the term: allotrope
Different structural forms of the same element, for example diamond and graphite are both made from carbon
What element is graphite made from?
Carbon
What element is damond made from?
Carbon
What is the structure of diamond?
Diamong is a tetraheadral structure, where each carbon is covalently bonded to 4 other carbons
What is the structure of graphite?
Graphite is layers of graphene sheets, with forces acting between the sheets. Each carbon is bonded to 3 other carbon atoms in a hexagonal structure
What is the difference between graphite and graphene?
Graphene is a single layer of hexagonal lattice structure, where a carbon is bonded to 3 other carbons. Graphite, is layers of graphene sheets
Can diamond conduct electricity?
No. There are no free electrons in diamond
Can graphite conduct electricity?
Yes. There are free electrons that can move throughout the structure
Why do giant covalent substances have high melting points?
They have high melting points because of the strong covalent bonds between the atoms
Explain how the structure and bonding of graphite makes it a suitable material for lubricants.
Graphite has a layered structure, with only weak forces of attraction between the layers. The layers can break away from each other, makng graphite soft and slippery
Describe the structure of fullerenes
Fullerenes are molecules of carbon, shaped likeclosed tubes or hollow balls. They have a huge surface area, so many catalyst molecules could be attached to each fullerene
Why is graphite used for electrodes?
Graphite has the ability to conduct electricity due to the free electrons. Carbon is also unreactive which makes it safer to use in electrodes
Where on the periodic table are metals found?
Towards the left of the periodic table
Describe the bonding in a metal
The bonding in a metal consists of strong electrostatic forces of attraction between positive metal ions and the delocalised electrons.
Explain why metals can conduct electricity
The have delocalised electrons that can pass through the structure
Explain why metals can conduct heat
The have delocalised electrons that can pass through the structure
Explain why metals are malleable and ductile
Mtels have a layered structure. The layers can slide across each other, meaning when a pressure is applied the layers move.
Explain why metals have a high melting and boiling point
Metals ions and the delocalised elctrons are held together by strong electrostatic forces of attraction. The electrostatic forces need a large amount of energy to be overcome
Define the term: Alloy
An alloy is a mixture of metals or a mixture containing at least one metal.
Why are alloys stonger than pure metas?l
An alloy has more than one type of atom. The atoms are different sizes, which makes it harder for the layers to pass over each other
What type of ions do metals form?
Metals always form positive ions
What type of ions do non-metals form?
Non-metals always form negative ions, due to them gaining electrons to gain a full outer shell.
Which group of elements is stable and doesnt form compounds easily?
noble gases/group 0 in the periodic table
Why do elements want to form bonds?
To gain a full outershell of electrons and become stable.
How is an elements electron arrangement linked to its position in the periodic table?
Elements in the same group have the same number of electrons in their outer shell.
How do positive and negative charges affect each other?
They attract each other.
Which sub-atomic particles of atoms take part in chemical reactions?
Electrons
What is an ion?
an atom that is charged because it has lost or gained one or more electrons
What happens when an ionic bond is formed?
One atom (a metal) loses electrons to another atom (a non-metal) to form oppositely charged ions that attract each other.
How is a positive ion formed and what is it called?
formed by the loss of electrons; cation
How is a negative ion formed and what is it called?
formed by the gain of electrons; anion
What are the forces called that hold ions together?
electrostatic forces of attraction
Why do atoms form ions?
to become more stable (like a noble gas)
What structure of regularly repeating ions do ionic compounds form?
lattice structure / ionic lattice
What is the name of the ionic compound containing calcium and bromine only?
calcium bromide
Describe the appearence of diamond
colourless and shiny
Describe the appearence of graphite
dark black/silvery
Describe the uses for diamond
Diamond is used for jewellery due to it’s appearance. Diamond is also used for drill bits - the covalent bonds mean that it extremely strong (one of the strongest known materials)
Desrcibe a use for graphite
pencils, lubricants - due to the layered structure it allows for movement and the covalent bonds meann it has a high melting point.
What is the molecular formula of the very common compound formed between hydrogen and oxygen?
H2O
What are molecules?
groups of atoms held together by (covalent) bonds
What happens to electrons between two atoms in a covalent bond?
they are shared
What kinds of bonds are found in molecules?
covalent bonds are found holding the atoms together in molecules (intermolecular forces are found between molecules)
Define: Intermolecular force of attraction
Forces of attraction between simple covalent compounds
In oxygen and carbon dioxide, the atoms share two pairs of electrons. How do we describe these bonds?
double bonds (represented by = in a displayed formula)
What is the name of the force that holds molecules together in gases and liquids?
intermolecular force
How strong are the forces of attraction between molecules compared to the bonds within molecules?
They are relatively weak. (Covalent bonds holding atoms together are strong / Intermolecular forces holding molecules together are weak)
Are simple molecules usually good conductors of electricity at room temperature?
No, they are poor conductors of electricity (as they have no charged particles or free electrons to move)
What type of structure do diamond and graphite have?
Giant Covalent
What type of structure does silicon dioxide have?
Giant covalent
