chem nov 1st (C1, C2) Flashcards
What is the main difference between a physical change and a chemical change?
In a physical change no new substances are made. In a chemical change at least one new substance is made.
What is the difference between a mixture and a compound?
In a compound the elements are chemically combined together. In a mixture the elements or components are not chemically combined together.
What can affect diffusion?
-temperature
-particle mass
-air particles/solvent particles can affect the rate
What are the arrangements of electrons called?
electron configuration
Metals are often malleable. What does this mean?
A malleable substance can be beaten or hammered into shape.
What are some typical properties of metals?
good conductors of electricity and heat, shiny, malleable, ductile, sonorous, high melting points
How are electrons arranged
in shells
how many electrons can the first shell hold
2
How many electrons can the second and further shells hold?
maximum of 8
What are some typical properties of non-metals?
poor conductors of electricity and heat, dull, brittle, low melting points
Sodium has 11 electrons, what is the electron configuration?
2,8,1
Which sub-atomic particle has the smallest relative mass?
Electron
what are the electrons in the outer shells that are involved in chemical bonding known as?
valency electrons.
Why do atoms have the same number of protons as electrons?
Atoms are neutral. The number of positive charges (protons) must equal the number of negative charges (electrons).
What are isotopes?
Isotopes are atoms of the same element with different numbers of neutrons.
why are helium, neon, argon and krypton so unreactive?
they all have 8 electrons in their outer shells or full outer shells
this means the atoms don’t lose or gain electrons easily.
what is formed when one of the reacting atoms is a metal and the other is a non metal?
an ionic compound. it is made up of ions.
what is an example of an isotope
Chlorine exists as two different chlorine atoms.
- chlorine 35 (17 protons 18 neutrons)
- chlorine 37 (17 protons 20 neutrons)
Why do isotopes of the same element have the same chemical properties?
as they have the same number of electrons in the outer shell which determines its chemical behaviour
Why are noble gases unreactive?
The noble gases have full outer shells, they do not easily lose or gain electrons.
Why are noble gases stable?
because they have full outer shells.
Why does a covalently bonded compound such as carbon dioxide have a relatively low melting point?
The intermolecular forces of attraction between the molecules are weak.
What will electron arrangements always match
A noble gas’s electron configuration (full outer shell)
What does carbon not form
ions
Would you expect a covalently bonded compound such as ethanol to conduct electricity? Explain your answer.
No. There are no ions or delocalized electrons present.
What are cations
positively charged ions
What are anions
negatively charged ions
Explain why a diamond has a very high melting point.
Each carbon atom is strongly covalently bonded to four other atoms forming a very strong giant lattice structure. A very high temperature is needed to break down the structure.
What is ionic bonding
The electrostatic attraction between oppositely charged ions
How is the structure of a graphite different from that of diamond?
Graphite, on the other hand, has a layered structure with each carbon atom forming strong covalent bonds with three other carbon atoms within each layer. Weak intermolecular forces hold these layers together.
What does electrostatic mean
stationary or slow-moving electric charges.
What patterns are ions in an ionic compound arranged into?
an ionic lattice
oxidation
metals lose electrons
reduction
non metals gain electrons
what are ions
atoms or groups of atoms that have gained or lost electrons
When an atom gains an electron how is that written in a diagram
(if it loses more than one it is written in front of the sign) - (minus)
What is ionic bonding between
metals and non metals
Describe how the arrangement of particles changes during melting.
the arrangement of the particles changes from orderly and tightly packed, to randomly arranged and tightly packed.
What do ionic substances consist of
non metals and metals
Describe how the arrangement of particles changes during evaporation.
During evaporation the arrangement of the particles changes from randomly arranged and tightly packed, to randomly arranged and spread apart.
Describe how the movement of particles changes during melting.
During melting, a solid becomes a liquid. In a solid, the particles vibrate on the spot, in a liquid they flow over each other
Describe how the movement of particles changes during evaporation.
During evaporation, liquid turns into gas. In a liquid, the particles flow over each other and interact, whereas in a gas the particles move around freely.
what subatomic particles stay the same in all atoms
protons
Describe the arrangement of particles in gas.
The particles are spaced far apart and in a random arrangement.
what are covalent bonds
a pair of electrons shared by atoms
Describe the arrangement of particles in liquid.
The particles are packed tightly together and have a random arrangement.
Describe the arrangement of particles in solid.
The particles must be packed tightly together and must all be touching in a uniform structure.
Describe the movement of particles in a solid
vibrate on the spot
Describe the movement of particles in a liquid
the particles can move over each other
whats an example of covalent molecules
Water (H₂O)
Carbon dioxide (CO₂)
Methane (CH₄)
Ammonia (NH₃)
Hydrogen chloride (HCl)
Describe the movement of particles in a gas
particles can move freely and are constantly moving in random directions
whats an example of giant covalent lattices
diamonds, graphite, silicon dioxide
polyatomic ions
Hydroxide OH⁻ -1
Carbonate CO₃²⁻ -2
Sulfate SO₄²⁻ -2
Nitrate NO₃⁻ -1
Hydrogen Carbonate HCO₃⁻ -1
Phosphate PO₄³⁻ -3
Ammonium NH₄⁺ +1
Explain why graphite has a high melting point.
- graphite is a giant covalent lattice
- many strong covalent bonds require lots of energy to overcome
Explain why diamond has a very high melting point.
- diamond is a giant covalent lattice
- it has a tetrahedral structure where each carbon is bonded to 4 other carbon
- need to break many covalent bonds which require lots of energy to break
What is an element?
a substance containing only one type of atom
What is a compound?
a substance containing two or more types of atoms chemically joined together
What is a mixture?
a mixture can contain elements and compounds but the substances are not chemically joined
What is nuclide notation?
nuclide notation shows the element symbol, proton (atomic number), and nucleon (relative atomic mass).
When will ionic compounds conduct electricity?
will conduct electricity in solution or molten, not when solid
What is a diatomic molecule?
a molecule made of only two atoms bonded together
What is a triatomic molecule?
a molecule made of only three atoms bonded together
What is valency?
the number of bonds an element needs to form
what are some properties of ionic compounds
High Melting and Boiling Points: Strong electrostatic forces between ions require a lot of energy to break.
Hardness and Brittleness: The rigid lattice structure makes them hard but brittle.
Solubility: Many are soluble in water, forming aqueous solutions.
Reactivity: Can react with other substances to form new compounds.
What are intramolecular bonds?
the forces that hold atoms together within a molecule
What are intermolecular forces?
the forces that exist between molecules, intermolecular forces are weaker than intramolecular bonds
What happens when a molecular substance is melted or boiled?
the strong bonds between atoms are not broken, the weaker forces of attraction between molecules are broken
Why does an ionic compound such as magnesium oxide not conduct electricity when it is solid?
The ions are held together strongly in a giant lattice structure. The ions can vibrate but not move around
what are ions in an ionic compound arranged into
ionic lattices
How does electrical conductivity change in ionic compounds
Ionic compounds will not conduct electricity when solid but will in solutions or molten.
are ionic compounds intermolecular forces strong or weak
strong
are simple covalent compounds intermolecular forces strong or weak
weak
Why do ionic compounds only conduct electricity when dissolved in a solvent?
When an ionic substance is dissolved in solution (or molten) the ionic lattice is is broken down allowing the ions to move freely. This allows conduction to occur.
structure of ionic compounds
Ionic compounds have a giant ionic lattice structure. This means they form a 3D structure with alternating positive and negative ions. The strong electrostatic attraction between these oppositely charged ions holds the structure together.
what are the intermolecular forces between the covalent molecule like
While the atoms within a covalent molecule are held together by strong covalent bonds, the forces between different molecules are much weaker.
characteristics of covalent molecular substances
Low melting points
low boiling points
what does volatile mean
evaporate easily
why do covalent molecules have low boiling and melting points
covalent molecules do not require as much energy to break bonds as the intermolecular forces are much weaker
properties of metals
strong, malleable, ductile, hard, high melting points & boiling points, sonorous, high tensile strength (maximum strength a material can be stretched with)
Why are metals good conductors of heat and electricity?
delocalised electrons which can move freely throughout the metal lattice, allowing for the easy transfer of heat energy and electric charge.
what is the definition of metallic bonding
It is the electrostatic attraction between positively charged metal cations and a sea of delocalised electrons.
Why are metallic compounds malleable and ductile
cations are organised in to layers which can slide over eachother.
What do imfs only apply to
covalent molecules
How do you differentiate between metallic, covalent or ionic bonds
Ionic bonds involve the transfer of electrons between atoms, forming oppositely charged ions that attract each other.
Covalent bonds involve the sharing of electron pairs between atoms.
Metallic bonds involve a lattice of metal ions surrounded by a ‘sea’ of delocalised electrons, allowing for high conductivity.
How are metallic compounds structured (draw it)
+ - + - + - + - + - = delocalised electrons
+ - + - + - + - + + = metal cations
+ - + - + - + - +
