Chemistry- Structures and Properties

kushagramodi56's version from 2015-04-26 11:30


Question Answer
What are atomsThey are the smallest unit of an element
What particles are atoms made up ofProtons, electrons and neutrons
What is the relative charge of protons+1
What is the relative charge of electrons-1
What is the relative charge of neutrons0
What is the relative mass of protons1
What is the relative mass of electronsNegligible
What is the relative mass of neutrons1
Where are protons locatedNucleus
Where are electrons locatedOrbiting nucleus
Where are neutrons locatedNucleus
What holds the most mass in an atomThe nucleus because protons and neutrons are heavier than electrons
Is the nucleus positively chargesYes because there are protons
What is the relation between electron shells and energy levelsThe closest shell to the nucleus has the lowest energy level
How many electrons can fit in the first shell2
How many electrons can fit in the second/third shell8
How reactive are full outer shellsThey re very stable and unreactive
How reactive are elements without full outer shellsThe least amount of elements in its outer shell are the most reactive
What does the number of electrons in its outer shell representGroup no.
What does the no. of shells representPeriod no.
What are grp 1 metals calledAlkali metals
What are grp 2 metals calledAlkaline earth metals
What are grp 7 metals calledHalogens
What are grp 8 metals calledNoble gases
Why are atoms neutral overallAs they contain the same amount of protons and electrons. Therefore, their equal and opposite charges cancel out.
What is the atomic numberThe amount of protons
What is the mass numberThe protons+ the neutrons
What do chemical properties depend uponThe no. of electrons
What do physical properties depend uponThe mass number
What are isotopesThey are atoms of the same element with the same amount of protons and electrons but a different amount of neutrons.
Why are grp 1 metals most reactiveAs they only need to lose 1 electrons which is easier in comparison to other grps.
What are ionsAtoms can obtain full outer shells by gaining/ sharing/ losing electrons when reacting with other atoms. They become ions. Therefore, they have an electric ch
What happens when they lose electronsThey have more protons meaning they are positively charged and called cations.
What happens when they gain electronsThey have less protons meaning they are negatively charged and called anions.
Define elementSubstances containing only one type of atom
Define compoundSubstances that contain 2 or more types of atom chemically bonded together
Why do atoms of element react to form compoundsSo they achieve full outer shells meaning they can be more stable.
What are the 3 types of bondingIonic, covalent and metallic bonding
What is ionic bondingOpposite charged ions are held together by sting electrostatic forces. It has to be between a metal and a non-metal. The metal loses its electrons and the non- metal gains electrons
What is covalent bondingShared pair of electrons. Both atoms of non-metals gain electrons by sharing.
What are electrostatic forcesForces which attract oppositely charged ions
What are the properties of ionic compoundsHigh m.p, soluble in water and able to conduct electricity.
Why do ionic compounds have high melting pointsThey gave strong electrostatic forces between oppositely charged ions which require large amount of energy to break
Why are ionic compounds soluble in waterWater breaks down the electrostatic forces allowing ions to fit between the spaces of the water molecules. Dissolve more quickly when heated/ stirred.
Why are ionic compounds able to conduct electricityAs charged ions are present. When solid, they are unable to move due to the electrostatic forces. When molten/ dissolved, they have weak electrostatic forces so they are able to move and conduct electricity.
What are the properties of simple covalent compoundsLow m.p and don't conduct electricity
Why do simple covalent compounds have low melting m.pAs they need less energy to overcome weak intermolecular forces meaning it is easier to pull the particles apart
Why can't simple covalent compounds conduct electricityThere is no overall charge so they can't carry electrical charge
What are intermolecular forcesForces of attraction between molecules
What are the properties of graphiteContain only carbon atoms, soft, high m.p. and can conduct electricity
Why is graphite softThere is weak intermolecular forces between the layers meaning they are easy to overcome so layers can slide over each other
Why does graphite and diamond have high m.pThe strong covalent bonds between the carbon atoms mean that lots of energy is needed to break these bonds
Why does graphite conduct electricityBecause each carbon atom only makes 3 bonds so the extra electrons is delocalised and can flow through the layers.
What are the properties of diamondContain only carbon atoms, hard, high m.p. and can't conduct electricity
Why is diamond hardThey have strong covalent bonds so they take lots of energy to break
Why does diamond not conduct electricityAll the electrons are involved in bonding meaning there is no overall charge
What are fullerenesThey are large- cage like structures made out of hexagonal rings of carbon atoms. They are very important in nano science applications and they can be used to deliver drugs to specific parts of the body.
What is nanoscience They refer to structures between 1-100 nm in size and have high surface area to volume ratio
How does bonding of pure metals occurMetals form great structures where they lose their outmost electrons and form cations which are arranged in regular lattice structures. There is now strong electrostatic forces between the +ve charged protons and -ve charged delocalised electrons creating a bond.
What are delocalised electronsElectrons that are free moving through a structure and are no longer associated with the atom
What are the properties of pure metalsThey have high b.p/m.p, conduct heat + electricity, malleable and ductile
What are alloysThey are mixtures of metals which are stronger and harder than pure metals.
What are shape memory alloysThey are alloys that can bend/ deform into different shapes. When they are heated they return to their original shape.