ATOMS AND MOLECULES PT 2 Flashcards
how does an element become an ion
An element becomes an ion when it has more or fewer electrons than protons
what are anions
Negative ions
what are cations
Positive ions
A loss of electrons from a neutral atom creates what
cation
A gain of electrons from a neutral atom creates what
anion
what type of element tends to form a cation and an anion respective of each other
metals > cations
non-metals > anions
what happens to atomic size from right to left of periodic table
Atomic size (radius) increases
why does atomic size change from right to left of periodic table
- effective nuclear charge increases (more protons) from left to right
- each additional electron is pulled more strongly toward the nucleus
what happens to atomic size from top to bottom of periodic table
Atomic size (radius) increases
why does atomic size change from top to bottom of periodic table
the atom becomes larger with each added shell
Why does atomic radii increase from top to bottom
each underlying period will have elements with an extra shell of electrons
explain the trend of the periodic table in atomic radii using the two elements of helium and lithium from group 8
helium has one shell and lithium has two shells
shell increase cos extra period down
thus atomic radii increases from top to bottom of periodic table
what is Ionisation energy
energy required to remove an electron from an atom
what happens if en electron is closer to the nucleus of an atom in regards to ionisation energy
If an electron is more strongly attached to the nucleus, it requires more energy to be removed
how does ionisation change from left to right of the periodic table
increases
how does ionisation change from bottom to top of the periodic table
increases
why does ionisation energy increase when going from bottom to top of the periodic table [2 marks]
- increased distance creates a decrease in electric field strength
- thus less energy is required to remove an electron
what happens to distance of electrons when moving down the periodic table
distance of the electron from the nucleus increases because there are more electron shells when going down the periodic table
what happens to ionisation energy as you move up the periodic table
distance of the electron from the nucleus increases because there are more electron shells when going down the periodic table
increased distance creates a decrease in electric field strength and thus less energy is required to remove an electron
what is electronegativity
the tendency of an atom to attract an electron in a bond that it shares with another atom
what is the trend of electronegativity from left to right and down to up of periodic table
Electronegativity tends to increase from left to right and from bottom to top
what is the bond between atoms of the same molecule called
interactions between atoms within the molecule are known as intramolecular bonds
what is the bond between atoms of different molecule called
interactions between atoms in different molecules are known as intermolecular bonds
what are the three main intramolecular bonds within molecules
ionic
covalent
metallic
what are the three main IMF bonds
Van der Waals
Dipole-dipole
Hydrogen bonds
what does IMF stand for
intermolecular bond
When does a covalent bond occur
when two electrons are shared by two nuclei
What happens to the electrons within a covalent bond
electrons (negatively charged) are pulled toward both positively charged nuclei via electrostatic forces.
How are electrons pulled towards both nuclei in a covalent bond
via electrostatic forces
What is a hydrogen bond a special circumstance of
special case of dipole forces
What is a hydrogen bond
is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule
In a hydrogen bond, what element is the electronegative atom within the interaction bond usually
Usually the electronegative atom is nitrogen, fluorine, or oxygen
What does NFO all have in common
has a partial negative charge
What happens to hydrogen when bonded to NFO
The hydrogen then has a partial positive charge as NFO all have a partial negative charge
If hydrogen is bonded to atoms with slight negative charges, what charge will hydrogen have
positive charge
What type of bond is an ionic bond
chemical bond
What does an ionic bond involve
involves the electrostatic attraction between oppositely charged ions
What is the primary bond that we observe from ionic compounds
ionic bonding
What are van Der waals interactions
interaction of electron clouds between molecules
What is the weakest intermolecular bond
van Der waals
What is a hydrophobic interaction
interactions are intermolecular and occur between non-polar substances.
What does hydrophobic bonds occur between
occur between non-polar substances.
When is a compound formed
when a substance contains one or more elements in a definite ratio
What is an example of an undeniable compound
water is a compound that contains oxygen and hydrogen in a definite ratio.
What is empirical formula
simplest whole number ratio between the number of atoms of the different elements in the compound
What is the formation of water as a symbol equation
2H2 + 02 > 2H20
What is the empirical formula of benzene
CH
What is the empirical formula of glucose
CH20
What is the MF of benzene
C6H6
What is the MF of glucose
C6 H12 06
What is the MF of butane
c4 h10
What is MF
the exact number of the different atoms that make up the molecule
What are ionic compounds named after
named after their cation and anion
When naming an ionic compound, how is the name positioning arranged
cation first
anion second
What are monoatomic and polyatomic ions given the name suffix of
-ide
In sodium chloride, which is the cation and which is the anion
Na+ = cation Cl- = anion
What do hydrochloric acid and sodium form to make
sodium chloride
What’s the symbol equation for the combination of Cl and Na
2Na + Cl2 > 2NACl
What is the law of conservation of mass
the number of atoms of a given element remains constant during the process of a chemical reaction
What are the four fundamental types of reactions
combination
decomposition
single displacement
double displacement
What is a single displacement represented in symbols
A + BC > B + AC
What is a double displacement represented in symbols
AB + CD > AD + BC
What is a synthesis reaction
where two or more elements chemically combine to give a compound
What is a decomposition reaction
compound if broken down to simple elements
What is a substitution reaction
an atom of group is replaced by another atom or group
What is a precipitation reaction
where a solid compound is formed when solutions of two soluble compounds are mixed
What is a neutralisation reaction
reactions where acid reacts with a base to give salt and water
What is a redox reaction
where electron transfer occurs
What does oxidised and reduced mean in terms of oxidation state
change in oxidation state
oxidised = increased oxidation state
reduced = decreased oxidation state
The oxidation number for an element can be calculated how
always 0
What is the oxidation number of a monoatomic ion
charge of the monoatomic ion
What is the oxidation number of all group 1 metals
+!
What is the oxidation number of all group 2 metals
+2
What is the oxidation number of Hydrogen
+1 when bonded to a nonmetal
-1 when bonded to a metal.
What is the oxidation number of Oxygen
- 1 in peroxides (O22-)—uncommon
- 2 in all other compounds—most common.
What is the oxidation number of fluorine
-1
What is the oxidation state of a poly atomic ion
charge on the polyatomic ion
What is an oxidising agent
agent will cause oxidation to occur, whilst the agent itself will be reduced.
What is a reducing agent
agent will cause reduction to occur, whilst the agent itself will be oxidised.
What happens when something is reduced
gains electrons.
What happens when something is oxidised
it loses electrons.
what is the sum of the oxidation numbers of all atoms in a neutral compound
0
