Chemistry Patterns Flashcards
What are atoms?
The smallest unit of matter.
What was john dalton’s model of the atom?
“billard ball model”
the atom is a ball-like structure
What was john dalton’s atomic theory?
- All atoms are indivisible
- atoms of the same element are identical
- different elements have different types of atoms
- all matter is composed of atoms
what were the benefits and limitations of john dalton’s theory
- identified all matter is made of atoms
- didn’t identify subatomic particles or nucleus
what was jj thomsons atomic model?
“plum pudding model”
Negatively charged particles in a spherical cloud of positive charge.
What was jj thomsons atomic theory
- atoms contain subatomic particles that are negatively charged.
- he named them corpscules
what were the benefits and limitations to jj thomson’s theory?
- didn’t identify nucleus
- identified electrons
what was ernest rutherford’s atomic model?
“nuclear model”
positive charge contained in the center with electrons orbiting.
benefits and limitations to rutherford’s model?
- identified an atom was made up of empty space
- identified the nucleus
-failed to explain the stability of an atom
*rutherford’s theory of atoms orbiting the nucleus failed to address that any charged particle in acceleration (which includes an electron in circular orbit) should emit electromagnetic radiation. As the electron emits this radiation, it would lose energy. the loss of energy should cause it to spiral into the nucleus and collapse it.
what was neil bohr’s atomic model?
“planetary model”
The electrons orbit the nucleus at fixed energies.
bohr’s theory?
Based on quantum theory that some physical quantities only take discrete values.
benefits and limitations to bohr’s model?
- explained the stability of an electron
- it failed to make correct predictions of large-sized atoms and explain the spectrum of atoms having only two electrons, such as the helium atom. The primary focus was on hydrogen, another limitation of the Bohr model.
- violates heisenberg’s uncertainty principle that we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy
where are electrons found?
orbiting the nucleus
where are protons and electrons
in the nucleus
explain the charge and mass of protons, neutrons and electrons
protons: positive charge, 1 mass unit
neutrons: no charge, 1 mass unit
electrons: negative charge, negligible mass
where is the atomic number on an element?
at the top of the box
where is the atomic mass on an element?
the decimal below the chemical symbol
where is the chemical on an element?
the big letters
explain groups and periods.
groups are the collums, and periods are the rows.
how to find the no. of
*valence electrons
*protons
the group no. is the no. of valence electrons.
The atomic number is the no. of protons.
how to find the no. of neutrons?
subtract the number of protons, or atomic number, from the mass number
what are physical properties?
properties that describe the physical characteristics of a substance, not how it behaves chemically.
examples of physical properties
- solubility
- viscosity
- ductilibility
- malleability
- boiling point
what are chemical properties?
properties of a substance that describe how that substance’s chemical composition will change.
examples of chemical properties.
- flammability
- radioactivity
- corrosiveness
- oxidability
- combustibility
- toxicity
- explosivity
why are noble gases (group 8) stable?
because they already have a full outer shell, therefore they do not have attraction to another.
what makes an electron raise to an excited state?
chemical energy such as radiation.
there are three properties.
what are the properties of ions?
> has a charge
has a different number of protons and electrons
has a full outer shell
what is a cation?
- ion with positive charge
- a metal
what is an anion?
- negative charge
- non - metals
how do you draw an ion?
- inside square brackets
- the new ion
- the number of electrons added or removed with a x/- symbol like you would with a power symbol
the number with the x/- symbol is determined by how many electrons were added or removed, and the x/- is the charge of the atom.
what is an ionic bond?
the transfer of electrons between a metallic atom and non-metallic atom
an ionic bond has:
an anion and cation
stable electron configuration is given by:
a full outer shell of valence electrons
how does an element go from neutral to an ion.
an ion has a full outer shell, making it stable.
from a neutral element, electrons need to be added or removed to make the outer shell full!
if electrons are removed, the ion is _____, if electrons are added, the ion is _____
positive, negative
an ion is written by
The atomic symbol with a no. and a +/-
* the number is the difference in electrons and protons
e.g Mg
protons = 12
electrons = 10 (2 , 8 configuration)
therefore = Mg^2+
covalent bonding is a ____ of electrons
sharing
to achieve a covalent bond, all elements need
full outer shells
what are the diatomic bonded elements? hint: use the mnemonic
hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine, bromine
HAVE NO FEAR OF ICE COLD BEER
A covalent bond can also be represented using
*lines between the elements (displayed formula)
*a dot and cross diagram
what is a diatomic bond
a bond consisting of two of the same atoms
what are the properties of acids?
*contain at least 1 hydrogen atom
*can be strong or weak
strong = dangerous and can burn through materials, e.g hydrochloric acid
weak = safe to consume, e.g carbonic acid
*can burn skin
*taste sour
*corrode metal
*turn blue litmus paper red
*pH less than seven
define an acid
a group of chemical compounds with similar properties
properties of bases
*“chemical opposites” of acids
*react with fats and oils to produce soaps
*taste bitter
*feel slippery/soapy
*turns red litmus paper blue
*pH greater than 7
*can conduct electricity
*has at least one hydroxide ion
bases that dissolve in water are:
alkalis
common indicators include (8)
- color change
-formation of a precipitate
-formation of a gas
-odor change
-temperature change
-sound
-litmus paper
-universal indicator
what is the role of indicators
the role of indicators is to show a chemical change has occurred
what is stomach acid
hydrochloric acid / gastric acid
formula for stomach acid and ph is
HCl, pH of 1 - 2 (highly acidic)
the roles of stomach acid
*denature (change of structure) of proteins
*activates some enzymes
*kills harmful microorganisms
properties of metals are
(5)
*can be hammered into thin sheets (malleability)
*ductile (can be drawn out into a thin wire
*good conductor of heat and electricity
*lustrous which means they have a shiny appearance.
*hard
properties of nonmetals are
(5)
*brittle
*bad conductors of heat and electricity (except graphite)
*non-lustrous (dull) and cannot be polished (except iodine).
*Non-metals may be solids, liquids or gases at room temperature
*most non-metals are soft
describe metallic bonding
a metallic bond is between two metals.
the valence electrons of all the metal atoms overlap, forming a lattice and a sea of delocalised electrons that can move through the whole structure. each atoms gives electrons to other atoms.
metallic bonds are very strong because of this constant attraction.
properties of salts
*hard
*brittle
*crystalline solids
*most salts are water-soluble
what is the neutralisation equation?
Acid + Base → Salt + Water
