2a:bonding and structure Flashcards
what are the types of strong chemical bonds?[3]
1.ionic
2.covalent
3.metallic
what is ionic bonding?
its when a metal atom reacts with a non metal atom and electrons are transferred from the metal atom to the non metal atom which makes them oppositely charged ions which are strongly attracted to each other and the strong electrostatic attraction holds the ions together in the ionic compound
what do non metals atoms become during ionic bonding?
non-metal atoms gain electrons and become negatively charged ions with a full outer shell
what do metal atoms become during ionic bonding?
metal atoms lose electrons to become positively charged ions with a full outer shell
how can ionic bonding be represented?
dot and cross diagrams
what are ions?
charged particles
why are ions formed?
to get a full outer shell like a nobel has(to have a stable electronic structure)
what charge of ions do group 1 elements form?
1+ ions
what charge of ions do group 2 elements form?
2+ ions
what charge of ions do group 6 elements form?
2- ions
what charge of ions do group 7 elements form?
1- ions
what is an ionic compound?
a giant structure of ions held together in a lattice by strong electrostatic forces(ionic bonds) of attraction between oppositely charged ions.
what are the pros and cons of using dot and cross diagrams for ionic compounds?
useful for showing how ionic compounds are formed
don’t show the structure of the compound,relative sizes of the ions or how they’re arranged
what are the pros and cons of using 3d models to represent ionic compounds?
show the relative sizes of the ions and the regular pattern in an ionic crystal
only lets you see the outer layer of the compound
what are the pros and cons of using ball and stick models to represent ionic compounds?
shows the regular pattern in an ionic lattice
shows how the ions are arranged suggests the crystal extends beyond what is shown
may shows the relative size of the ions
sometimes ions are not shown to scale
suggests there are gaps between ions when there isn’t
how would you find the empirical formula from a dot and cross diagram?
count how many atoms there are of each element(so if there two chlorine atoms and one calcium atom then its CaCl2)
how would you find the empirical formula from a 3d model or a ball and stick model?
you need to balance the charges of the ions so the overall charge of the compound is zero.
eg.Na+ has a 1+ charge and Cl- has a 1- charge so you only need one of each ion to balance the charges so the empirical formula is NaCl
why do ionic compounds have high m.p and b.p?
they are giant structures with strong electrostatic forces of attraction between oppositely charged ions so large amounts of energy is needed to the break the many strong bomds
are ionic compounds soluble?
most ionic compounds dissolve easily in water
do ionic compounds conduct electricity?
not when solid because the ions are all held in fixed positions but when melted or dissolved,the ions are free to move and they’ll carry electric charge
when is a covalent bond formed?
when a pair of electrons are shared between two non metal atoms
why do atoms share electrons?
to get a full outer shell
why are covalent bonds strong?
the positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces which makes covalent bonds strong
how can you represent covalent bonding?[3]
1.dot and cross diagrams
2.displayed formula
3.3d models
4.stick and ball models
what are the limitations of using dot and cross diagrams for covalent bonding?
useful for showing which atoms the electrons in covalent bond come from
don’t show the relative sizes of the atoms or bow the atoms are arranged in space
what are the limitations of using displayed formulas for covalent bonding ?
useful for showing how atoms are connected in large molecules.
don’t show the 3d structure of the molecule or which atoms the electrons in the covalent bond have come from
what are the limitations of using 3d model for covalent bonding?
shows the atoms and their arrangement in space
can get confused for large molecules where there are lots of atoms to include and don’t show where the electrons in the bonds have come from
how could you find molecular formulas of a simple molecular compound from a given diagram for covalent bonding?
counting how many atoms there are of each element
what are simple molecules made up of?
a few atoms joined by covalent bonds
what are examples of simple molecules?
hydrogen,hydrogen chloride,methane,ammonia,water
what are examples of simple molecules that often form a single covalent bonds?
hydrogen(H2),Chlorine(Cl2),
how many covalent bonds are there in Methane and why?
4 because carbon has four outer electrons and hydrogen has 1 and only need to form one covalent bond to achieve a full outer shell. So carbon would form a covalent bond with 4 hydrogen atoms to form methane molecule.