Types of Substance - Topic 1 Flashcards
Describe the appearance of metals:
- Metallic
- Shiny
Describe the melting and boiling points of metals:
- High boiling point
- High melting point
Describe the strength of metals:
- Strong
- Malleable
What is the physical state of metals at room temp?
- Solid
- mercury is an exception
Malleability:
ability to be bent into different shapes
Describe the malleability of metals:
Malleable
Ductility:
ability to be drawn into wires
Describe the ductility of metals:
Ductile
Describe the electrical conductivity of metals:
Good conductors of electricity
Describe the appearance of non-metals:
Dull
Describe the melting and boiling points of non-metals:
- Low melting point
- Low boiling point
Describe the strength of non-metals:
Weak
Describe the malleability of non-metals:
Brittle
Describe the ductility of non-metals:
Not ductile
Describe the electrical conductivity of non-metals and what is the exception:
- Poor conductors of electricity
- Graphite is an exception
Describe the thermal conductivity of non-metals:
Poor conductors of heat
Describe the density of metals:
have a high density
Properties of ionic compounds class practical: What is the apparatus needed?
- beakers
- compounds from table
- spatulas
- equipment to make a circuit
- glass rod
- test tube
Properties of ionic compounds class practical: Method
- Describe the appearance of all the compounds.
- Put a spatula of magnesium oxide into a test tube and heat for one minute at the tip of a blue flame. This is the hottest part of the flame. (it doesn’t melt showing that magnesium oxide has a high melting point)
- Add a few spatulas of the solid to a small beaker, construct a circuit to test the conductivity of the solid.
- Add 20-30 mls of water to the solid. Does it dissolve? Stir with a glass rod to help.
- Construct a circuit to test the conductivity of the solution if the compound dissolves.
Why does magnesium oxide have a higher melting point than sodium chloride?
- The higher the charges of the ion the stronger the bonding (due to stronger electrostatic forces of attraction between them)
- The stronger the bonding the more energy needed to break the bonds
What two materials are ionic compounds formed between?
metal and a non-mental
What do metals do to obtain full outer shells and what do non-metals do to obtain all outer shells?
- in general metals lose electrons to obtain a full outer shell of electrons like a noble gas
- non-metals gain electrons to get a full outer shell
What type of ions do metals form and what type of ions do non-metals form?
- in general, metals form positive ions - cations
- non-metals form negative ions - anions
How are ionic compounds formed?
ionic compounds are formed by the transfer of electrons between atoms to produce cations and anions
What do ionic compounds look like?
ionic compounds and solutions of group 1 and 2 are white powders and ionic compounds that have transition metals are different colours
Describe the structure of ionic compounds:
- between a metal and non-metal
- positive and negative ions (oppositely charged ions) are held tightly/close together by strong electrostatic forces of attraction in all directions between oppositely charged ions in a giant regular lattice structure - these forces are called ionic bonds
- consists of a regular arrangement of ions
What is the bp and mp of ionic compounds like?
high melting points and boiling points due to their being strong bonds between the ions (caused by strong forces of electrostatic attraction) requiring a lot of energy to be overcome so have high mp’s and bp’s
Do ionic compounds conduct electricity as solids?
- Ionic compounds will not conduct electricity as solids - due to the fact that ions are not free to move through solid structure as all the charged ions are arranged in a fixed position in a lattice so cannot conduct electricity despite being charged particles as they are not free to move
- despite having charged particles (ions) due to the regular arrangement of the ions in a lattice and the ions are held together by strong ionic bonds (strong electrostatic forces of attraction) between oppositely charged ions so the ions are closely packed together and so when an ionic compound is solid it can’t conduct electricity as the ions can’t move
Do ionic compounds conduct electricity as liquids (when molten or in aqueous solution)?
- ionic compounds do conduct electricity as liquids when in an aqueous solution as the ions can move and carry charge as the ions are surrounded by water molecules causing the lattice to be broken down (popped apart) (and the water cuts down the forces between the ions) so the ions become separated allowing the ions to be able to move and carry current/charge
- ionic compounds do conduct electricity when molten as the heat energy overcomes the strong ionic bonds (strong electrostatic forces of attraction) between oppositely charged ions which allows the ions to move freely so therefore ionic compounds conduct electricity when molten
Are ionic compounds heat compounds?
no ionic compounds are not heat compounds as ions aren’t free to move as they are in a fixed lattice when solid
Are ionic compounds soluble?
- they are generally soluble in water as the ions are surrounded by water molecules and the lattice is popped apart
- they often dissolve in water to form an aqueous solution
How strong are ionic compounds?
they are hard but brittle as when a layer of atoms is moved the layers repel each other and the object shatters
Describe the structure of simple covalent substances:
- non-metal + non-metal
- molecules that consist of just a few atoms held together by covalent bonds
- these molecules are bonded together by a shared pair of electrons, which forms the strong covalent bond
- between molecules, weak intermolecular forces hold the molecules in either a solid, liquid or gaseous arrangement
What are the mp and bp of simple covalent compounds like?
- mp and bp points are low - many are either liquids or gases at room temperature
- to melt//boil a simple covalent bond you only need to break the intermolecular forces between molecules which are weak so require less energy to break so covalent compounds have low mp’s and bp’s
Do simple covalent compounds conduct electricity?
- no because it is simple covalent and simple covalent compounds exist as molecules
- electrical conductivity is low/poor as for a substance to conduct electricity the substance has to have charged particles that are free to move (free electrons) - molecules are neutral
- Substances that consist of small molecules don’t conduct electricity, because small molecules do not have an overall electric charge
Do simple covalent compounds conduct electricity as a solution?
- Substances that consist of small molecules don’t conduct electricity, because small molecules do not have an overall electric charge
- Although, some breakdown in water to form ions which can conduct electricity
Are simple covalent compounds soluble?
- many are insoluble in water, but some are soluble because they can form intermolecular forces with water which are stronger than those between water molecules or their own molecules already (e.g. CO2and NH3are soluble)
- solubility in water is variable
- oxygen dissolved in water, ammonia dissolves in water, methane dissolves in water, HCl dissolves in water
- substances chemically similar to water dissolve in water
Describe the general structure of giant covalent structures:
- non-metal + non-metal
- a three-dimensional structure of atoms that are joined by covalent bonds
What is the mp/bp of giant covalent structures like?
very high mp and bp due to strong covalent bonds between the carbon atoms which require a lot of energy to be overcome
Are giant covalent compounds soluble?
- They are Insoluble in water as giant covalent substances cannot form these strong attractions with water, so they are insoluble as all the electrons are held tightly between the atoms, and aren’t free to move
Do giant covalent structures conduct electricity?
- most substances with giant covalent structures have no charged particles that are free to move - this means thatmost cannot conduct electricity
- graphite, a form of carbon which can conduct electricity as it has delocalised electrons which carry charge and can move which are found between the layers of the graphite
Describe the structure of metallic bonding:
- atoms in a metal are held together by metallic bonding and are arranged in a regular pattern (lattice) and are closely packed together.
- in a metallic structure positive metal ions (consisting of the nucleus and inner shell electrons) are held together by the outer shell electrons which become delocalised (ie no attached to one particular atom and with a certain freedom to move)
- electrostatic forces if attraction between the positive metal ions (cation) and the delocalised electrons
- all metal have positive charges
- there are no non-metals to give the extra electron to so instead the electrons are removed from the atoms outer shell and then float in between the cations - so the delocalised electrons are free to move through the whole structure
- the higher the charge on the metal and the more delocalised electrons found in between the cations the stronger the bonding also the sharing of delocalised electrons gives rise to strong metallic bonds
- number of delocalised electrons tells us which group the metallic structure is in
- if the temperature increases the ions will vibrate on the spot due to having more energy
What is the mp and bp of metals like?
high mp’s and bp’s as there are strong electrostatic forces of attraction in metallic bonds between positive ions and delocalised electrons
Can metals conduct heat?
- metals can conduct heat do you to having delocalised electrons that are free to move through the metallic structure
- the delocalised electrons are given kinetic energy which means they can move through the lattice randomly and knock into ions and so can provide heat energy to ions o the other side of the lattice much faster
Can metals conduct electricity?
metals are good conductors of electricity as they have delocalised electrons that can carry charge and move through the lattice
How strong are metals?
- metals are malleable and ductile
- metals are ductile and malleable as the layers of atoms in metals can slide over each other without bonding being affected and without breaking any bonds (due to delocalised electrons) - graphite (giant covalent structure) graphite can conduct electricity for the same reason
Are metals soluble?
metals are insolubledue to the strong electrostatic forces of attraction between the delocalised electron and the cations in the lattice - however some metals may react with water
Alloys:
mixtures of metals where the different metals are metallically bonded together in a giant metal lattice e.g. bronze, stainless steel
Why aren’t alloys regarded as compounds?
not a compound as there aren’t a fixed ratio of atoms of each type of elements in the lattice