Unit 1 Test Review Flashcards
What is the periodic law associated with the organization of the periodic table?
-elements are arranged in order of increasing atomic number
-elements with similar physical and chemical properties occur at regular intervals using this order
*DIMITRI MENDELEEV
What are the three basic types of elements found on the periodic table?
Metals
Non-metals
Metalloids
Describe metal elements
state: solid except mercury
physical properties:
-hard, lustrous
-good conductors of heat and electrical current
-malleable and ductile
Describe non-metals
state: many gas, some solid, one liquid (bromine)
physical properties:
-non-lustrous
-poor conductor of electrical current and heat
-brittle and non-ductile
Describe metalloids
state: all
physical properties:
-good conductors of electrical current
-poor conductors of heat
-brittle
What is a period?
-a horizontal row on the periodic table
-period number indicates the energy level (shell) of the valence electrons
What is a group/family?
-vertical column on the periodic table
-group number indicates valence electron number
What are the standard states of all elements?
solid
liquid
gas
What are synthetic elements?
-elements that are outlined with a black border and white fill
-they are synthetically produced via nuclear fusion in nuclear reactors or particle accelerators
In what category are most elements involved in creating living tissue found?
other non-metals
Why does each period end with a noble gas
each noble gas has a stable amount of electrons
What is an atom?
the building block of matter
make up everything but energy
-the smallest particle of an element that still retains the identity and properties of the element
What are atoms made out of?
3 subatomic particles:
-neutrons
-protons
-electrons
Explain the electron arrangement in atoms
-according to Borh’s diagrams, electrons exist in orbits around the nucleus
-each orbit has a specific level of energy associated with it
-the further away an electron is from the nucleus, the more energy the electron possesses
-electrons in the outermost orbit are called valence electrons, and they help form chemical bonds between atoms
-when electrons are removed, they gain a positive charge and these are called cations
-when electrons get added, these are negative and called anions
What does it mean for an atom to be isoelectronic?
have the same electron count as an ion present on the periodic table
What is the bond definition of a non-polar covalent bond, and the physical properties it may exhibit?
-the bond shows two elements that are shared equally because their electronegativity rates are close in amount
-the bond is then neutral through this process
physical properties:
-soft due to weak intermolecular forces
-low melting and boiling points
What is the bond definition of a polar covalent bond, and the physical properties it may exhibit?
-made up of cations which have a positive charge, and anions which have a negative charge and when they bond they neutralize as opposites attract, the transfer of electrons to non-metals allows this to occur
physical properties:
-brittle
-high melting points and boiling points
What are isotopes?
-atoms of one element that differ by the number of neutrons in the nucleus
What is atomic number?
-the number of protons present in the nucleus of an atom
-identifies the element (different elements don’t share atomic number)
-isotopes of one element have the same atomic number
What is mass number?
-the sum of the protons and neutrons present in the nucleus of an atom
-isotopes of one element have different mass numbers *NOT THE SAME AS ATOMIC MASS
-the isotopic mass number is not found by using the periodic table
What are stable isotopes?
-isotopes that share the same physical and chemical properties
What are radioisotopes?
-unstable isotopes as they have unstable amounts of protons and neutrons
-the nucleus is destabilized
-these unstable nuclei are radioactive, and they emit radiation through particles when they attempt to re-stabilize
What are the three types of radiation?
-alpha, beta, gamma
What are the uses of radioisotopes?
agriculture: added to fertilizer
food preservation: slows down spoilage
medicine: disease treatment
electricity generation: nuclear power plants
archeology: carbon dating
How do you determine the subatomic particle counts for the isotopes of atoms?
number of protons: atomic number
number of electrons when neutral: the same as the atomic number
number of neutrons: mass number - atomic number
How do you represent an isotope in atomic notation?
mass number
X
atomic number
How do you represent an isotope in isotopic notation?
X-mass number
What is isotopic abundance?
-the amount of a given isotope of an element that exists in nature, expressed as a percentage of the total amount of the element
-the average atomic mass which appears on the periodic table is a weighted average that factors in the mass of all the naturally occurring stable isotopes to their percentage abundance
What is the equation for calculating the weighted atomic mass of a naturally occurring isotope?
wam = (% isotope #1 x mass isotope #1) + ((% isotope #2 x mass isotope #2) +….
percentage expressed as decimal, divided by 100!
What is the atomic radius?
-the approximate distance from the
centre of the nucleus to the
the approximate outer boundary of the
cloud-like region of its valence
electrons
Describe the trend of atomic radius as you travel up and down a group
atomic radius INCREASES DOWN a group
WHY?
-moving down a group, each subsequent element has one additional orbit
thus the valence electrons are further away from the nucleus
-further away from the nucleus, the valence electrons experience less attractive forces from the nucleus
Describe the trend of atomic radius as you travel from left to right across a period
atomic radius DECREASES ACROSS a period
WHY?
-the number of protons in the nucleus increases so the nucleus gets stronger and pulls the outer electrons closer
What is an ionic radius?
the radius of the stable ion of an atom
What is the trend when comparing a neutral atom to a stable ion?
cations: removal of electrons (+ charge)
-have a smaller radius than a neutral atom because there is one less orbit so the valence electrons are now closer to the nucleus
anions: adding of electrons (- charge)
-anions have a larger radius than those of a neutral atom because the nuclear charge stays the same however the gaining of electrons makes the repulsive forces increase (enlarged electron cloud)
What is first ionization energy?
the energy needed to remove a valence electron from a neutral atom to form a positive charge
What is the trend associated with the first ionization energy when you travel down a group?
first ionization energy decreases down a group
-attraction between the nucleus and electrons in the valence shell decreases down a group because atomic radius increases, meaning that less energy is needed to pull an electron away from the atom
What is the trend associated with the first ionization energy when you travel across a period?
first ionization energy increases across a period
-attraction between the nucleus and electrons increases as the atomic radius decreases, causing more energy to be needed to remove an electron and pull it away from the nucleus
What is electron affinity?
-the ease at which an atom can add a valence electron into its outer orbit to form a negatively charged ion
What is the trend associated with electron affinity (electro negativity) when you travel down a group?
electronegativity decreases down a group
-since atomic radius increases down a group the attraction between the valence electrons and the nucleus decreases, thus the ability to attract electrons into its outer orbit also decreases
What is the trend associated with electron affinity (electro negativity) when you travel across a period?
electronegativity increases across a period
-since atomic radius decreases across a period the attraction between the valence electrons and the nucleus is stronger, thus the ability to pull in electrons into the outer orbit and attract them increases
What do Lewis dot symbols show?
-the element symbol with valence electrons represented
What are the basics of chemical bonding?
chemical bonds form when atoms transfer or sharing valence electrons
-atoms bond with other atoms to achieve stability
-chemical stability is achieved when the valence shell of an atom is full, equal to the electron count of the nearest Noble Gas
-a stable valence shell is either 8 or, for a few elements, 2 electrons
-a full valence shell of electrons lowers the overall
energy of the atom and thus provides it with stability
-when atoms/ions share the same electron configuration
they are said to be isoelectronic
What are intramolecular bonds?
Intramolecular bonds form between atoms within a molecule or
compound.
What do ionic bonds consist of when they chemically bond?
electrons are transferred from one atom to another
-forms between a metal and a non-metal
-metal atoms easily lose electrons and become CATIONS as they are left with an overall positive charge
-nonmetal atoms easily gain electrons and become ANIONS as they
are left with an overall negative charge
-the cation and anion are strongly held together by electrostatic
forces of attraction (opposite charges attract)
-the overall bond remains neutral since the ion charges cancel
each other out
-referred to as ionic compounds made up of formula units
What do covalent bonds consist of when they chemically bond?
-electron pairs are shared between two non-metals
-called molecular compounds
What is a polar covalent bond?
electrons are shared unequally
-the shared electron pair spends more time closer to the atom with
the greater electronegativity (greater attraction for the electrons) causing the more electronegative atom to develop a
slightly negative charge while the less electronegative atom in the
bond is left with a slightly positive charge
What is a non-polar covalent bond?
electrons are shared equally
-both atoms involved in the bond have essentially the same
electronegativity (degree of attraction for shared pair of
electrons)
-the bond is neutral
What is electronegativity?
-the relative ability of an atom to attract a shared electron pair
when bonded
-the type of bond that forms between two atoms can be determined
by calculating the electronegativity difference between them
-metals have lower electronegativity as they lose electrons
-non-metals have greater electronegativity as they gain electrons
How do you determine what bond forms between two atoms when labelling them as polar, non-polar, or ionic?
ELECTRONEGATIVITY SCALE
-less than 0.4 then the bond formed is nonpolar covalent
-between 0.4 to 1.7 then the bond formed is polar covalent
-greater than 1.7 then the bond formed is ionic
*however regardless of electronegativity difference if a bond
forms between a metal atom and a non-metal atom it is always ionic
How do metal atoms achieve stability?
-Metal atoms achieve stability through chemical reactions with other atoms (namely non-metal atoms)
-A metal atom reacts to achieve stability by losing one or more electrons from its valence shell, resulting in the formation of a positively charged ion (CATION)
What is metallic character?
-The chemical properties exhibited by metals are dependent on howeasily they lose electrons to form positively charged ions (cations)
-The easier a metal atom can lose the electrons from its valence shell
the more chemically reactive it is and the more metallic character it
has
How do non-metal atoms achieve stability?
-Non-metal atoms achieve stability through chemical reactions with
other atoms (both metal and non-metal atoms)
-A non-metal atom achieves stability by gaining one or more electrons into its valence shell resulting in the formation of a negatively charged ion (ANION) or
by sharing pairs of electrons with another atom
What is a non-metallic character?
-The chemical properties exhibited by non-metals are dependent on how easily they draw electrons into their valence shell either through accepting via transfer or by sharing
-The easier a non-metal atom can attract electrons into its valence shell the more chemically reactive it is and the more non-metallic character it has
