⭐️SC5, SC6, SC7, Ionic, Covelant Bonding And Substance Types Flashcards
What are bonds?
Forces of attraction that hold atoms together
Why do atoms form ions?
To gain a full out shell by gaining or loosing electrons
What is a cation?
A positive ion
What’s an anion?
A negative ion
What is the force of attraction between positive an negative ions?
Electrostatic forces of attraction
What is an ionic bond?
The electrostatic forces of attraction between oppositely charged ions
What will atoms that easily form ions have?
A nearly full or near,y empty outer shell of electrons
What do ionic compounds often form as solids and why?
Crystals due to their regular lattice structure
What structure do ionic compounds always have?
A regular giant ionic lattice structure
What properties do ionic compounds have?
- high melting and boiling points
- don’t conduct electricity as a solid as ions are fixed
- easily dissolve in water
When will an ionic compound conduct electricity?
as an aqueous solution or as a liquid as the ions become free to move and carry a charge
Which ionic compounds have higher melting points than the rest?
Ions with higher charges as it takes more energy to overcome the electrostatic forces of attraction
What former covenant bonds?
Non metal atoms by sharing a pair of electrons
What holds together atoms in a molecule?
Covenant bonds with strong electrostatic forces of attraction between the positive nuclei and negative electrons in the bonded atoms
What kind of forces are there between molecules?
Weak forces of attraction
How big are atoms?
Around 10^-10 meters in diameter
What is the valency of an element?
The number of covenant bonds formed by atoms of different elements
How do you find the valency of an element?
By finding the number of electrons needed to obtain a complete full outer shell
What’s the valency of Si?
4
What’s the valency of F?
1
What are the positives and negatives of 2D representation models
+ show what atoms the substance contains and and how atoms are connected
-don’t show the shape of the substance, or size of atoms
What are the positives and negatives of dot and cross diagrams?
+ where the electrons un the bonds or ions came from
-don’t show the size of the atom/ion or how it’s arranged
What are the positives and negatives of 3D models?
+show the arrangement of ions
-only show outer layer of substance - electrons can’t be seen
What are the positives and negatives for the ball and stick model?
+help to visualise structures by showing the shape of the lattice in 3D, more realistic than 2D drawings
-make it look like there’s a big gap between atoms when really this is where electron shells interact, they don’t show correct scales of atoms or ions
What bonds hold together atoms of a molecule and what is their structure?
Covenant bonds, simple molecular structure (e.g. water)
Why do simple molecular structures have low boiling points?
As they have weak intermolecular forces that don’t need much energy to overcome
Why don’t simple molecules not conduct electricity?
As they have no overall charge and so can’t carry an electrical current
Why doesn’t the covenant bond itself not allow simple molecules to carry a charge?
As strong forces between -electrons and +nuclei hold electrons in place and can’t flow so can’t carry a current
What is a monomer?
A small simple molecule that can be joined in a chain to form a polymer
What are polymers?
A chain of covalently bonded carbon atoms
Why do longer polymers have higher melting points than shorter ones?
As longer ones have more intermolecular forces between them and the longer chains get tangled with each other
What is the definition of an allotrope?
Different structural forms of the same element
Describe the structure of fullerenes
Each carbon atom is covelently bonded to 3 others and the structure of molecules are often tubular or spherical
Explain the properties of fullerenes
- Low melting points because of weak intermolecular forces
- soft and slippery due to weak intermolecular forces
explain the structure of graphene
It’s similar to fullerene but isn’t a simple molecule and consists of sheets of carbon atoms with no fixed formula
Explain the properties of fullerenes
- lightest known material as each sheet is one atom thick
- good electrical conductor as it allows free electrons to move across its surface
- it’s very strong due to covelant bonds
Give two covalent giant molecular structures which are allotropes of carbon
Diamond and graphite
Visualise the structure of graphite and diamond
Use page 45 of Pearson active chemistry for answer
Explain the properties of graphite
- has high melting point due to many covenant bonds that must be broken
- conducts electricity due not all electrons being held in covalent bonds giving allowing delocalised electrons to freely move and carry a charge
Why is graphite a layered structure?
As it has 3 covalent bonds to every carbon atom
Explain some properties of diamond
- has high melting point as it’s got many strong covalent bonds
- very hard due to the 4 covalent bonds to every carbon atoms giving it a tetrahedral arrangement
- doesn’t conduct electricity as all electrons are strongly held in place with covalent bonds
Give some uses of graphite
- Used as a lubricant as each sheet is held by weak intermolecular forces allowing the layers to slide past each other
- used in electrodes as it conducts electricity well
Give some uses of diamond
- Used to cut things due to its rigid ness
- electrical insulator as it has no free charged particles
Give some common properties of metals
- solids with high melting points
- shiny when polished
- malleable
- high density
- good conductors of electricity
Give some common properties if non-metals
- solids, liquids or gases with low melting points
- not usually shiny(when solid)
- brittle (when solid)
- low density
- poor conductors of electricity
What structure do atoms in a metallic element make?
A giant lattice
What is metallic bonding?
The electrostatic attraction between positive metal ions and the negative delocalised electrons
Why are metals good at conducting electricity?
Because their outer shell electrons are lost from each atom. This leaves a giant lattice of positive metal ions surrounded by a sea of delocalised electrons
Why are metals malleable?
As when a metal is hit, the layers of ions slide over each other and the sea of delocalised electrons hold the ions together so the metal changes shape without breaking
What happens to electrons when a potential difference is applied to two point of a metal?
The electrons will flow towards the positive side as they transfer energy and form a current
Aluminium forms A^3+ ions. Why does it have a higher electrical conductivity than sodium?
As magnetism forms the Mg 2+ ion and so doesn’t contribute as many electrons to the sea of delocalised electrons as Al 3+ does which has 3 electrons to contribute
What is the structure of ionic compounds?
Billions of ions held together in a lattice
What are the properties of ionic compounds?
- high melting/boiling points
- many are soluble in water
- conduct electricity when liquid or in a solution
What are the properties of simple molecular covalent structures?
- low melting/boiling points
- few are soluble in water
- most don’t conduct electricity
Where are giant covalent structures found?
In some non-metal elements and some compounds of non-metals
What is the structure of metallic bonds?
Billions of ions held together in a giant lattice structure of positive ions and a sea of delocalised electrons
