Unit 1 Test Flashcards
Matter and bonding
Atomic number tells us what?
of protons and electrons ( only if atom is electrically neutral) what atom it is
How to find # of neutrons
Atomic mass - protons
isotopes
an element with the same about of protons but differing neutrons
Isotopic abundance
the percentage of each isotope that exists in nature
RadioIsotope
radio active isotope with a unstable nucleus that breaks down
How is isotopic abundance relative to atomic mass
Atomic mass is the average mass of all isotopes x their isotopic abundance
What is an atom
Empty space with a central nucleus and surrround by electron cloud
What is the nucleus made up of
Protons and neutrons
Atomic mass = what?
The mass of all the neutrons and protons ( electrons basicly weigh nothing)
What is paleoclimatology
The study of ancient climate change using isotopic abundance
periodic table is broken into what groups
alkali metals
alkali earth metals
transition metals
non metals
metaloids
inner transition metals
halogens
noble gases
actinods
lanthernoids
representive metals ( everything but transiiton metals)
Cations
Metals that lose electrons to become positive charged ions
Anions
Non metals that gain electrons to become negativity charged ions
Periodic law
elements arranged in order of increasing atomic
elements with similar
chemical properties appear periodically
Chemical Reactivity
similar # of valance electron = similar chemical properties
Atomic Radius
length from center of nucleus to outermost electron
What happens to the atomic radius when you go down a group
Atomic radius increases because there are more shells = more shielding electrons which block the attraction between the nucleus and the outer most electron, electrons repel spreading out
what happens to atomic radius when you move across periods
when you go left to right across and period the atomic radius decreases because there are more protons without an additional electron shell = higher effective nuclear charge ( attraction) to pull in the electrons
Cations become smaller why?
lost of an electron which increases effective nuclear charge ( more attraction between nucleus and electron bring the electrons closer) which makes the atom smaller
Anion become bigger Why?
Gain of electrons decreases effective nuclear charge causing the electrons to repel and spread out ( atom gets bigger)
Ionization Energy
the energy required to remove the outer most electrons from neutral atom
what happens to the ionization energy when the atom is smaller
it increases because the attraction to the nucleus is greater ( effective nuclear charge) needed more energy to remove the outer electrons
what happens to the ionization energy when the atom is bigger
it decreases because the attraction between the electrons and the nucleus is lower due to shielding electrons
Why are atomic radius and ionization energy trends the opposite?
When atomic radius decreases ionization energy increases
when atomic radius decreases ionization increases
successive ionization energies
when trying to remove a core electron the ionization energy is very high because the electrons are held closer to the nucleus due to the effective nuclear charge is very high
electronegativity
tendency for a bonded atom to attract electrons
decreases going down groups increases moving left to right in periods
why do smaller atoms have high electronegativity
smaller atoms have a greater effective nuclear charge causing the electrons to be closer to the nucleus so the smaller atom will hold the shared election closer to its self then the larger bonded atom
when do the protons stay in the nucleus
the protons are attracted to the neutrons
what is nuclear force
the attraction between the protons and neutrons that is holding the nucleus together
what is ionic radius
the distance from the outermost electron to the nulcues of an ion
what are ions
atoms that have gained of lost electrons which now have a positive or negative charge
what are sheilding electrons
an extra shell of electrons that block the attraction between the outermost electron and the nucleus
lewis dot diagrams
symbol= nucleus and core electrons
draw valance electrons
unpaired electrons= bonding electrons
paired electrons= lone pairs
ionic bonding
metal and non metal
transfer of electrons
electrostatic attraction between ions
solid at SATP
form crystal lattice
END> 1.7
why do ionic compounds exist as solids at room temperature
the electrostaic attarction between the cations and the anions is very strong = atoms are held very close together
why do ionic compounds dissovle is water
the cations and anions of ionic compounds are attraction to the postive and negative dipoles of the water molecules surounding the ions breaking the ionic bonds
why do ionic compounds have a high melting point
ioninc compounds have high melting points do to their strong electrostatic forces holding them together, a greater amount of energy is need to break the crystal lattice and overcome the ionic bonds
why do ionic compounds conduct electrcity
when dissolved in water ionic compounds separate into cation and anions that move around bringing charge through the water
why can you crush ionic compounds
ionic compounds form brittle ridge crystal lattices that when pressure is aplied crush into smaller piecies
molecular compound
covalent bonds
intermolecular forces
electronegativites to close to transfers electrons
share electrons
two non metals
form single unit molecules
pure covalent bond
END < 0.4
equal sharing of electrons
polar covalent bond
0.4> END < 1.7
unequal sharing of electrons
partial charges
cooridnate covalent bond
when one atom provides both electrons for a shared pair
why do molecular compounds have low melting points
intermolecular forces are weaker than ionic bonds less energy is need to overcome the attraction
do molecular compounds dissolve in water
pure covalent molecules do not dissolve in water do to the lack of oppsite charges to be attracted to the dipoles of water molecules
polar covalent molecules can dissolve in water due to their partial charged dipoles that attacted to the the dipoles of water molecules
what is a polar molecule
partially negative and positive ends (poles)
can have polar bonds but not be a polar moleclue
1 line of symmertry
do molecular compounds conduct electricity
pure covalent molecules do not conduct electricity lack of oppsitie charges to charge the water
polar molecules are partial conductors do to partial charges that bring charge through the water
molecular compound hardness
intermolecular forces are weaker than ionic bonds and do not form crystal lattices this causes molecular compounds to be more flexible and compressable
what are intramolecular forces
the forces of attraction within a molecules or compound
( chemical bonds)
ionic bond
covalent bond
poalr covalent
cooridnate covalent
what are intermolecular forces
forces of attraction between neighbouring molecules
forces that hold molecules together is solid or liquid state
much weaker then intramolecular forces
what are the 3 types of intermolecular forces
London dispersion forces
Dipole- Dipole forces
hydrogen bonding
what is london dispersion forces
attraction of a molecules electrons to neighbouring molecules protons
very temporary
larger the molecule larger LDF
EXIST IN ALL SUBSTANCES
what is dipole dipole forces
electrostatic attraction between polar molecules
weaker then ionic ( partial charges)
MUST BE POLAR MOLECULE
PCl3
what are vanderwaals forces
LDF and Dipole Dipole happening at the same time
what is hydrogen bonding
extreme case of dipole dipole when hydrogen is bonded with O, N or F = VERY larger END
NOT A CHEMICAL BOND
strongest intermolecular force
h20
what are chemical bonds
the forces of attraction holding atoms togther
the octet rule
generalization stating that when atoms combime the combime so each atom achieves 8 valance electrons
whats another name for ionic compounds
salts
when can metals exist on their own and why are they such good conductors
they are swimming in a sea of electrons allowing charge to move freely
how do intermolecular forces affect boiling point
Substances with strong intermolecular bonds have higher boiling points
Difference between ionic molecular and ion
Ionic - crystal lattice negatives and positives
Molecular - sharing of electrons forms molecules
ions- has a charges because of extra electrons or less electrons
Why do not all ionic compounds dissolve
Some ionic compounds electrostatic forces are stronger then the attraction between the anions and cation with the water so the crystal lattice doesn’t break into anions and cations
Why does oil float on top of water
Water is more dense due to hydrogen bonding
Oil is a non polar molecule held by LDF which created no partial charges
Water isn’t attractted to the oil molecules only it’s self
Why does ice float
ice forms hydrogen bonding force is strong it acts like a bond locking water molecules is crtystal lattice shape
Less dense because of orientation of water when it cools it explands more space between molecules
what are chemical bonds
forces of attraction holding atoms tog
why do atoms form chemical bonds
electrons move around in enegry levels the outermost level ( the valance shell) to become stable wants to reach a full octet of 8 electrons
