Unit 9 Flashcards
Ammonium ion
NH4 ( small 4 )
Carbonate ion
CO2- ( up) and 3 down
Hydroxide ion
OH -1 (up)
Nitrite ion
NO -1 (up) and 2 ( down )
Nitrate ion
NO -1 (up) and 3 down
Sulphate ion
SO -2 ( up) and 4 down
Sulphite ion
SO -2 (up) and 3 down
Hydrogen carbonate ion
HCO -1 (up) and 3 down
What is Nicotine
C10H14N2 is a naturally occurring alkaloid compound from the nightshade family of plants. Used as a stimulant and anxiolytic .
What is valency
Valency refers to the number of electrons an atom has to lose or gain to have a full outer shell ( combining power )
Where are electrons found
In shells orbiting teh nucleus of teh atom
What does the location of an element on the periodic table tell us ?
Groups numbers show valency and periods show number of shells
Electron configuration
Representation of arrangement of electrons among the orbital shells and sub shells
What are teh three types of bonds
- Covalent bonds
- Ionic bonds
- Metallic bonds
Ionic bonding ( 4 )
• occurs between metal and non-metal atoms.
• Electrons are transferred between atoms
• This produces ions (charged atoms)
Forms metal compounds
Properties of ionic compounds
- high melting and boiling points
- forms giant crystalline lattice structures
- Ionic compounds can conduct electricity if dissolved or molten
Covalent bonding ( 3 notes )
● Non - metal atoms like to covalently bond
● Sharingofelectronswithinachemicalbond
● Toobtainafulloutershellofelectrons
What happens in an ionic bond ( 2 )
In ionic bonds the metals lose electrons ( t become a positively charged cation ) and the non metals accepts these electrons to became a negatively charged anion.
What is an ionic bond
Electrostatic force of attraction between a positive metal and a negative non metal ( between oppositely charged ions )
Lattice energy
Energy required to convert one mole of an ionic solid into its gaseous ionic constituents
What is lattice enthalpy and what does it depend on
- Lattice enthalpy is teh measure of strength of forges between teh ions in an ionic compound.
- depends on ionic radius and charges of ions
What is electricity
Flow of electrons ( slat does not conduct electricity in its solid state )
Why do ionic compounds have high melting and boiling points (3)
This so because ionic compounds are held together by strong electrostatic forces between oppositely charged ions. These forces are known as ionic bonds. Because the ionic bond ( lattice ) contains so many ions a large amount of energy is needed to overcome these bonds,
Electrical condictivulty property of ionic compounds explanation
When molten or aquas teh ions are free to move around, mobile charged particles are needed to conduct electricity. The solid lattice does not allow ions to move from tehir fixed positions. In liquids this sold lattice is broken and ions can move free,y and therefore conduct electricity.
What causes ionic crystals to shatter
If the crystalline structure was places under stress, like being hit by a hammer, this could result in a shit in Teh planes of ions. I’d ions of teh same charge came into contact, teh repulsive forces would cause the crystal to shatter
Why are some ionic compounds less soluble
When teh charges are greater or ions are in closer proximity. The bonds between teh ions are stringer, so teh ions are less attracted to the polar water molecules. As a result tehy are less soluble
What does teh molecular formula of a compound describe ?
The actual number of individual atoms in a molecule of teh compound
Metallic bonds result from ?
Electrostatic attraction between a lattice of positive ions and the delocalized electrons. The attraction between delocalised electrons and the positive ions in a regular lattice.
What are delocalized electrons
Electrons that are free to move throughout a whole structure
What are ions and how are they formed and why are they charged ?
An ion is a charged particle. They are formed when atoms gain or lose electrons to form a full outer shell. Ions are charged because the number of protons is different from the number of electrons.
When are covalent bonds formed and what do they occur between
A covalent bond is formed when two atoms share electrons to obtain a noble gas configuration. Covalent bonding occurs between non-metal atoms.
are ionic or covalent bonds stronger
Generally, ionic bonds are much stronger than covalent bonds. In ionic bonds, there is complete transfer of electrons between elements to form a stable compound. While in covalent bond, there is only sharing of electrons between two elements to form a stable compound.
Two types of structures formed by covalent bonding
molecular covalent structures. Simple molecules held together by weak forces of attraction. Examples include iodine, methane and carbon dioxide.
giant covalent structures. Many atoms joined together by strong covalent bonds. Large and variable number of atoms. Examples include diamond and graphite.
van der Waals’ (3)
Intermolecular attractions found between molecules of substances . Distance dependent, do not result form a chemical electronic bond. Relatively weak when compared to ionic and covalent bonds . Two types exist : London dispersion forces and dipole-dipole forces
Electron charge density
The chance that an electron of an atom is in a certain area in the electron cloud at a specific time is called the “electron charge density.
Polarizability
The ability of a molecule to become polar and displace its electrons is known as the molecule’s “polarizability.”
Physical properties of molecular covalent structures (not giant )- 3
- low melting and boiling points ( Little energy is needed to break the weak van der Waals’ forces between the molecules )
- do not conduct electricity or heat. Covalent molecular structures do not conduct electricity because the molecules are neutral and there are no charged particles
-insoluble in water. Most covalent compounds are insoluble in water. Hydrogen chloride and ammonia are exceptions, because they react with water.
Allotropes
Allotropes are different forms of the same element, in the same state. Graphite,graphene and diamond are allotropes of the same element (carbon) in the same state (solid).
The carbon atoms in a diamond form a ?
The carbon atoms in a diamond form a regular tetrahedral structure.
What are teh three main types of metal lattice structures ?
Face-centered cubic ( FCC ), body-centered cubic ( BCC ) and hexagonal close packed ( HCP )
How are the valance electrons placed in ionic bonding
Ionic bonding is the complete transfer of valence electron(s) between atoms.
What does ionization energy mean ?
Energy required to remove an electron from the outer electron shells.
Why are metals mealleable (2)
Malleability is caused by metallic bonds that have freely moving electrons that allow the atoms in the metal to shift and slip past each other when a physical force is applied. Consist of layers of atoms
The metal cations are surrounded by electrons, teh positive ions can slide over and under one another without causing disruption to teh metallic bonding
Phosphate ion
PO -3 ( up ) and 4 down
What are 2 thing polarizability depends on
The more electrons a molecule contains, the higher its ability to become polar. Polarizability increases in the periodic table from the top of a group to the bottom and from right to left within periods. This is because the higher the molecular mass, the more electrons an atom has. With more electrons, the outer electrons are easily displaced because the inner electrons shield the nucleus’ positive charge from the outer electrons which would normally keep them close to the nucleus.
2.distance of electrons from nuclear charge
Basically less control the nuclear charge has on the charge distribution the higher teh polarizability
Why do different ion pairs in lattice bonds stay together ( include what would make them repel each other )
In addition to the force of attraction between the individual pairs force of attraction also exists among the oppositely charged ions of different pairs that bring them close to each other. Alfie result of this repulsive forces are also generated between similar ions of different pairs.
Because the cation to cation distance ( measured from the centre ) of different pairs are greater than the cation to anion distance, the force of attraction is greater that teh repulsive forces and the ions arrange themselves in such a way that a potential energy becomes a minimum.
When is complete transfer of electrons not possible ( ionic binding is not possible when ? )
When the elements do not differ much in their electronegativities the complete transfer of electrons is not possible between the atoms, in this case the electrons are shared and covalent bonds are formed. Also note - each atom contributes an equal number of unpaired electrons towards the bond formation (covalent )
What is bond length
The distance between the nuclei of the atoms after the formation of the bond is called the bond length
London dispersion forces
London dispersion forces are the weakest type of intermolecular bond. London dispersion forces are caused by an uneven distribution of electrons within an atom. This results in a slightly negative () and slightly positive charge on either side of the atom. A temporary dipole has been established. This temporary dipole can induce a temporary dipole on a neighbouring atom/molecule.
Fajan’s rules
- Size of cation and anion - a large cation and small anion results in maximum ionic character for the bond
- Charge of Cation and Anion - low charge on cation and anion results in maximum ionic character for the bond ( high charge leads to maximum covalent charector )
According to Fajans’ rule, an ionic bond is formed by a compound with a low positive charge, a large cation, and a small anion, whereas a covalent bond is formed by a compound with a high positive charge, a small cation, and a large anion
What does teh strength of a covalent bond depend on ?
Teh strength is related to the extent to which the two combing atomic orbitals can overlap. Teh greater the extent of overlap between teh atomic orbitals, the greater is the strength of resulting covalnet
What are sigma bonds ( what is it and electron distribution )
Formed as a result of maximum overlapping of orbitals along teh inter nucleus axis ( end-end or head on ). This type of overlapping is stronger. Electron cloud is distributed in a cylindrically symatrical way around teh inter nucleus axis.
Pi bond ( what is it and distribution of electron cloud )
Formed between two atoms by lateral overlapping of orbitals perpendicular to teh interernucleur forces axis ( sideways overlapping ). Results in a weak bond. Electron cloud is distributed in two npbana shaped regions above and below the inter nucleus axis
How is a double bond formed in oxygen2 atoms
Singly occupied 2p z orbital of oxygen atom overlaps ( end to end ) with teh same orbital of another oxygen atom to give rise to a sigma bond, . Singly occupied 2p y orbitals of both the oxygen atoms overlap along a line perpendicular to z-axe to give a pi bond. Thus a double bond is formed.
What is hybridization ?
Process of intermixing of two or more atomic orbitals of almost equal energies of an atom and their redistribution into an equal number of identical orbitals, teh resultant orbitals are called hybrid orbitals
how are ionic bonds associated with some covalent characters - 3 points
Ionic bonding is presented as the complete transfer of valence electrons, typically from a metal to a non-metal.
All bonding interactions have some covalent character because the electron density remains shared between the atoms. The degree of ionic versus covalent character of a bond is determined by the difference in electronegativity between the constituent atoms. The larger the difference, the more ionic the nature of the bond.
Phosphate ion
PO -3 ( up ) 4 down
Dipole moment
Quantitative measure of polarity of the molecule
Octet rule
States that atoms of an element have the tendency to attain the nearest inert gas configuration either by the transfer of electrons of by teh sharing of electrons
How was Lewis’s theory of formation of covalent bond through electron sharing interpreted
The mechanism of sharing of electrons was interpreted with teh help of teh concept of overlapping orbitals after teh quantum mechanical model of atom was proposed
Coordinate covalent bond ( also known as a dative bond )
Special type of covalent bond in which only one pair of teh participating atoms contribute to teh electron pair for sharing . Because I hwo teh contribution of electrons are one sided a slight polarity develops in Teh molecule
Structure of Diamond (3)
- each carbon atom is joined to four other carbon atoms by covalent bonds
- the carbon atoms form a regular tetrahedral structure
- no delocalized electrons
Properties of Diamond ( 5)
- very hard ( Rigid network of carbon atoms held together by strong covalent bonds )
- does not conduct electricity (No delocalised electrons to conduct electricity )
- insoluble in water (Not a polar molecule (does not attract water molecules))
- colorless and transparent
- high melting point
Uses for Diamond
Cutting tools, such as diamond-tipped glass cutters and oil rig drills.
Structure of graphite (5)
• each carbon atom is joined to three other carbon atoms by covalent bonds
• the carbon atoms form a hexagonal layered network structure
• the layers have weak intermolecular forces between them and can slide over each other • each carbon atom has one un-bonded outer electron
• these un-bonded electrons are delocalised, and are free to move
Properties of graphite (4)
• Can conduct electricity. ( Delocalised electrons are free to move through the structure of graphite)
• Slippery texture (The layers in graphite can slide over each other because the intermolecular forces between
them are weak.)
• Black, shiny and opaque • High melting point
Uses of graihute ( 3 )
• useful for electrodes in batteries and for electrolysis. • useful as a lubricant (bicycle chain oil)
• Pencil lead
Structure of buckministerfullerene (5)
• Made up of 60 carbon atoms joined together by strong covalent bonds.
• Molecules of C60 are spherical.
• Hexagonal rings of carbon atoms joined by covalent bonds.
• Hollow shape.
• Weak intermolecular forces between molecules of buckminsterfullerene.
Properties of bickministerfullerene (3)
• Cannot conduct electricity between molecules but can within itself. ( Delocalised electrons stay inside the hallow structure, they cannot travel between molecules)
• Slippery (Week intermolecular forces make it slippery and have a low melting point)
• Low melting point compared to other giant covalent structures
Uses of buckministerfulerene (3)
• Drug delivery within the body.
• May be used to store hydrogen, possibly as a fuel tank for fuel cell powered cars. • Used as an anti-aging and anti-damage agent in the cosmetic sector
Graphene structure (2)
• Single layer of graphite
• Each carbon is covalently bonded to 3 other carbon atoms
Properties of graphene
• has a very high melting point • is very strong
• Conducts electricity
• Lightweight and flexible
• Transparent
Uses of graphene (4)
• useful in electronics
• anti-corrosion coatings and paints
• efficient solar panels • Drug delivery
Nanotubes structure ( 4 )
• A layer of graphene, rolled into a cylinder.
• Each carbon is covalently bonded to 3 other carbon atoms
• The length of a nanotube is very long compared to its width, so nanotubes have high length to
diameter ratios. • Hallow centre
Properties of nanotubes ( 4 )
• has a very high melting point • is very strong
• Conducts electricity
•high tensile strength, so they are strong in tension and resist being stretchedt
Uses of nanotubes
• Can be added to other materials, for example in sports equipment, to make them stronger. • Drug delivery
• Nanotechnology
Properties of covalent compounds (4)
- usually liquids or gases
- low melting and boiling pints
-do not conduct electricity - usually insoluble in water
Ionic compounds properties
-forms crystals
-high melting and boiling pints
-hard and brittle
-good infiltrators
Conduct electricity ehn dissolved in water
Metals ionization energies vs covalent and ionic bonds
Cocaine
C17H21NO4
Cocaine is a stimulant drug obtained from the leaves of two Coca species native to South America
Cocaine
C17H21NO4
Cocaine is a stimulant drug obtained from the leaves of two Coca species native to South America
What is a chemical bond
The attractive force which holds together the atoms or group of atoms in a chemical species is known as a chemical bond
Explain teh structure of an ionic lattice (2)
Ions have a regular repeating structure called an ionic lattice. teh lattice is formed because the ions attract each other and form a regular pattern woth oppositely charged particles next to each other.
What is an alloy
A mixture of two or more elements where atleast one element is a metal.
Why are metals malleable/ductile
Metal ions are arranged in layers. These layers can slide over each othe
Gant vs molecular covalent structures
The key difference is that simple covalent molecules have a small and fixed number of atoms, while giant structures have large and variable numbers of atoms.
What results in metallic bonding
Sharing f delocalized electrons ( The electrons from the outer shells of the metal atoms are delocalised, and are free to move through the whole structure )
Why are metals good conducts
they are electrical conductors because their delocalised electrons carry electrical charge through the metal
they are good conductors of thermal energy because their delocalised electrons transfer energy
Why do metals have High melting and boiling points “
they have high melting points and boiling points, because the metallic bonding in the giant structure of a metal is very strong - large amounts of energy are needed to overcome the metallic bonds in melting and boiling
Explain alloy hardness ( when is a metal string - force - + why are pure metals soft + hwo do alloys help make them stronger )
In the solid state, a pure metal has a giant metallic structure. The atoms are arranged in layers. When a force is applied, the layers may slide over each other. The greater the force needed, the harder and stronger the metal.
In an alloy, there are atoms of different sizes. The smaller or bigger atoms distort the layers of atoms in the pure metal. This means that a greater force is required for the layers to slide over each other. The alloy is harder and stronger than the pure metal.
Structure of a metal
The metal atoms are arranged in a regular pattern of layers, with delocalised electrons able to move between them.
Electrons on teh oute shells of the metal atom are free to move
One limitation,of teh dot and cross diagram
A dot and cross diagram shows the pairs of outer electrons, and which atoms they have come from. It does not show how the atoms are arranged in space.
Why are ionic compunds brittle but metal not
Application of a force results in like-charged ions in the crystal coming too close to one another, causing the crystal to shatter. When a force is applied to a metal, the free-flowing electrons can slip in between the stationary cations and prevent them from coming in contact.
Melting and boiling pints do simple covalent molecules
Low melting and boiling pints taht increase with increasing molecule size due to increased intermolecular forces
Graphite is a good conductor because ?
Free delocalized electrons in a 2D LAYERED structure
Where is teh spare electron in graihute
Deloclased and occcipies teh space in between teh layers
Graoh we structure in one line
Infinite lattice of covalent,y bonded atoms in two dimensions ( bonded tighter in a repeating oattern of hexagons )
Factors that effect strength of metallic bonds
Total number of delocalized electrons.
Magnitude of positive charge held by the metal cation.
Ionic radius of the cation
lattice dissociation enthalpy
standard enthalpy change that occurs on the formation of 1 mole of gaseous ions from the solid lattice
Hierarchy
Hierarchy in a business refers to the organization structure based on a ranking system
Line manager
The person directly above employee on the next hierarchical level is known as the line manager
What is a line manager responsible for ?
A line manager is responsible for the day-to-day management of the people that directly on the next level below in the hierarchy
Advantages of using hierarchical structures (
- They show clear lines of authority
- establish departments or teams to create a sense of belonging
- Rather inflexible (may pose an issue when external changes require teh organization to be flexible
- Departmentalization means workers are isolated from their official teams
Chain of command
The chain of command refers to the formal line of authority through which communication and orders are passed down in an organization
Bureaucracy
Bureaucracy is the execution of tasks that are governed by official administrative and formal rules of an organization .
Characteristics of bureaucratic organizations (3)
Prescribed rules and policies, standardized procedures and formal hierarchical structures
Centralized structure
Decision making is made done by a very small number of people in the center without consultation with other members in the the organization
