Atomic structure Flashcards
how many electrons are in the second shell of an atom?
8
how many electrons are in the third shell of an atom?
18
how many electrons are in the fourth shell of an atom?
32
what is ionic bonding?
a metal + non-metal bonding together
what is electrovalent bonding?
a metal + a metal bonding together
what happens when you heat a small piece of sodium on a defragerating spoon and plunge into chlorine?
combining the silver shiny metal (sodium) with the green gas (chlorine) is quite a violent reaction with a white taken and forms a white solid (salt) sodium chloride
how many electrons are in the first shell of an atom?
2
The difference between an element and a compound
elements are mad of atoms with the same number of protons in the nucleus whereas compounds are two or more different elements chemically bonded together in fixed proportions by mass
distinguish the term between atom and an ion
an atom has an equal number of protons and electrons as it is neutral whereas ions have a different amount
what is a positive charge of a particle called?
cation
what is a positively charged particle called?
anion
what is a particle called when it is neutral?
atom
what is a particle called when negatively charged?
electron
what is a positively charged ion called?
protons
when two solutions mix together and form a solid, what is the solid called?
a precipitate
what is the definition of a covalent bond?
it is the electrostatic force of attraction that two nuclei have for a shared pair of electrons
what is ammonia?
NH3
what does the atomic number show us?
The amount of protons
what does the mass number of an atom tell us?
how many neutrons there are + protons
how do you work out the radiuS of an atom?
1 x 10to the 10- (m)
how do you work out the radius of the nucleus?
1 x 10 to the -15 (m)
wht do the protons equal?
electrons
How do you work out the charge of an atom?
protons - electrons
what is the definition of an isotope?
Isotopes are the atoms of the same element which differ from each other by having differing numbers of neutrons in the nucleus (as the atoms are the same element, isotopes of the element all have the same number of protons in the nucleus)
a b
C
d
What does B =?
the charge
how do you know if isotopes are radioactive
The nucleus is unstable and could split apart
when a compound has ionic bonding, decried it’s structure.
it will have structures made up of positive and negative ions- oppositely charged ions are held together by electrostatic forces in a giant lattice…. SOLID STATE ions are arranged as giant ionic crystals aswell as in the lattice LIQUID STATE ions are close but in an irregular formation GASEOUS STATE ions are far apart moving freely
what is the structure of sodium chloride?
a giant 3D cubic lattice
Electrostatic forces are strong
they have strong attraction between the oppositely charged ions, these require a lot of energy to break them… with ionic compounds it will take a lot of heat to melt them (why compounds have higher melting points)
what are the differences between ionic substances and covalent substances?
ionic substances usually dissolve in water but not in non-polar solvents- covalent is the other way round.
Ionic substances conduct electricity in water and when melted but not when it’s in solid state- covalent bonds don’t
how do covalent bonds form?
the are formed by the process of sharing a pair of electrons
what are the two structures of covalent bonding?
simple molecules or giant lattices
what bonding does covalent have?
the bonding is strong between the covalent bonds within the molecules but there are weak forces between the molecules.
what is the covalent bonding in a solid state?
the molecules are arranged as molecular crystals with the molecules in a lattice.
what is covalent bonding in a liquid state?
molecules are close together but arranged irregularly.
what is covalent bonding in gaseous state
the molecules are far apart and move freely
Gaseous molecules do not themselves break up into atoms and it requires breaking of strong covalent bonds
what are the forces between molecules joined covalently?
by covalent bonds which are strong and can have a number of bonds interlocking the compound but keeping the compounds near each other are intermolecular forces which are weak, and it is easier to break them apart- they have high and low melting points
the solid state of a molecular crystal
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which bonds are stronger, covalent or intermolecular
covalent
what does lattice mean?
regular
what must an ionic substance have to conduct electricity what must it have?
either ions or electrons which are free to move
explain about the conductivity of simple covalent substances
there are no free ions and the electrons are held tightly in covalent bonds- they are not free to move so it’s cannot conduct electricity
explain the conductivity with substances of a covalent giant lattice
there are no free ions and electrons are held together tightly in covalent bonds so are not free to move, therefore do not conduct electricity….. There is one exception
do covalent compounds conduct electricity
no
what is the one exception to covalent conductivity?
Graphite
how does graphite conduct electricity?
The C atom uses 3 of its outer electrons to form 3 covalent bonds and a layer of interacting hexagons are formed. The are many layers and they are held together by weak forces. The fourth outer electron is delocalised between the layers and can move through the lattice parallel to the layers a potential is applied (a battery is attached)
what is electricity?
a stream of moving charges and in order for a substance to conduct electricity it must have either ions or electrons which are free to move.
explain the conductivity of ionic bonding (solid state)
There are ions present in the solid but because they are held tightly in a lattice and are not free to move, ionic substances do not conduct electricity in solid state.
explain the conductivity of ionic bonding in liquid state
The ions are free to move, therefore ionic substances will conduct electricity when in liquid state
describe the conductivity of ionic bonding in gaseous state
Ions are free to move and therefore ionic substances will conduct electricity
what is a negative electrode?
cathode
what is a positive electrode?
anode
explain the circuit of electrolysis
the battery pumps the electrons out from its negative terminal. these flow through the wire to the cathode, they circuit cations which react with the electrons forming a simple metal for example calcium= Ca++ + 2e- > Ca. The negative ions goto the anode and the give up an electron to the anode forming atoms: The. the electrons go back to the batter as the elections are moving in the wire and the bulb lights up
explain the melting and boiling points of ionic compounds
these compounds all have high melting points - making them all solids at room temperature…. it takes a lot of energy to break them up as the have strong electrostatic forces between the oppositely charged ions in the lattice
explain the melting and boiling points of covalent compounds
these compounds have low melting points- usually liquid or gases at room temperature… it does not require a lot of energy to break the forces holding the molecules together, but the more electrons there are in the molecule the stronger they are, however between the molecules are not usually broken on eithe melting or boiling
explain the melting and boiling points with covalent giant lattice bonding
these ci pines have very high melting pings as the covalent bonds need to be broken to melt them and covalent bonds are strong. when the covalent bonds break the substance often feel directly from a solid to a gas. The tend to be all solids at room temperature
explain the solubility of ionic compounds
these compounds are usually soluble in water but not in non-polar solvents such as ethanol
explain the solubility of covalent bonds (simple molecular)
these compounds are soluble in non pair solvents but not in water
explain the solubility of covalent bonding (giant lattice binding)
they are not soluble in any solvent
what is simple molecular bonding
when a substance goes around in twos e.g I2 , it is held together by intermolecular forces ( weaker than covalent )
what is giant lattice bonding
when a simple substance bonds together e.g K… It is bonded together by covalent bonds (which are stronger than intermolecular forces)
what is the definition of metallic bonding?
it is the electrostatic attraction of positive ions for a sea of delocalised electrons
name the properties of giant ionic lattices
hard, brittle crystalline solids with high melting points. usually soluble in water but insoluble in nonpolar solvents.mDo no conduct electricty in water, made up of positive ions and negative, but held together by strong electrostatic forces in a giant lattice. They conduct electrocity in aqueous state because the ions are free to move and it is these that carry the current through the substance
give the properties of covalent simple molecular lattices
soft, low melting point solids. Soluble in non-polar solvents but insoluble in water. Doesn’t conduct electricity when solid, molten(liquid) nor when dissolved in non polar solvents as there are no ions and electrons are held tightly in the covalent bonds and are not free to move about. They are made up of simple molecules. The covalent bond holding the molecule together is strong but the forces between molecule are weak
name properties of giant metallic lattices
hard ( if covalent lattice extends in all three dimensions) or flaky( if the lattice is in two dimensions). crystalline solids with very high melting points, insoluble in virtually all solvents. Does not conduct electricity as electrons are held tightly in covalent bonds and are not free to move about (except graphite). made up of atoms joined to each other by covalent bonds in an extended lattice
describe the properties of giant metallic lattices
usually hard with high melting points but does not apply to the alkali metals. Malleable and ductile. Good conductors of heat and electricity in both solid and liquid state. soluble in liquid metals but usually in other insoluble in other solvents. The more reactive the metals are the more likely to react with water - not dissolving. Made up of ions in a sea of delocalise electrons. They conduct electricity because their electrons are free to move
why do some elements react together but others do not
when two atoms collide it is their electrons which come into contact and not their nuclei, therefore chemical combination must involve electrons. Moreover it must involve the outermost or valency electrons.
what is it called when you share electrons?
covalent bonding
what is it when loosing or gaining electrons
ionic bonding
OILRIG
oxidation is loss, reduction is gain
what name is used to describe atoms which have the same atomic. um er but different mass numbers?
isotope
what is the valency for ammonia
NH4 +
what is an isotope?
an element has the same number of protons and electrons but a different number of neutrons
what is a period of the periodic table
Periods in the periodic table. In each period (horizontal row), the atomic numbers increase from left to right. The periods are numbered 1 through 7 on the left-hand side of the table. Elements that are in the same period have chemical properties that are not all that similar.
what is a group of the periodic table
a group (also known as a family) is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table, but the f-block columns (between groups 2 and 3) are not numbered.
explain in terms of electronic structure why neon is unreactive
it has a stable electron arrangement with 8 electrons in outer shell, so cannot easily gain or share electrons
