Unit A.2 Science 10 Flashcards
What are the 6 properties of metals?
- Shiny/Lustre
- Malleable & Ductile
- Silver/grey in color
- Good conductors of electricity & heat
- Most metals are solid at room temp (25c)
- Some metals react strongly with other substances
How many elements are there and how many naturally occurring ones?
There are 115 basic elements, 90 are natural, 25 are manmade/synthetic
What 3 classes are elements divided into?
Metals, Non-metals & metalloids
What is the exception metal that isn’t solid at room temp
Mercury, it melts at -39C
What does inert mean and what are 2 metals that are like that?
Inert means unreactive and it’s gold and platinum
How many non-metal elements are there?
17
Why are non-metals grouped together?
Because of their lack of resemblance to metals
What is the most stable group in the periodic table
Group 18; the noble gases
What is silicon used for?
Computer chips
Is hydrogen a metal or non-metal?
Non-metal
What are the 5 properties of non-metals?
- Dull
- Brittle
- Poor conductors
- Can be gas, liquid or solid at room temp
- Low melting point
How does the periodic table organize elements?
According to it’s chemical properties
Where are the 3 classes on the periodic table?
Metals of far left, Non-metals on right and Metalloids along the staircase that starts from carbon
Name the 4 group names of the periodic table you should’ve memorized
Group 1: Alkaline Metals
Group 2: Alkaline- Earth Metals
Group 17: Halogens
Group 18: Noble Gases
Who invented the periodic table?
Dimitri Mendeleev in 1872
How are the rows numbered and how are the groups/families numbered?
Rows are horizontal and they go from 1-7
Groups are vertical and they go from 1-18
How much of an atom’s mass does the nucleus account for and why?
The nucleus accounts for 99.9% of an atom’s mass because the rest of the atom is just empty space with electrons in energy levels and they’re vv small
Electron’s take up 99.9% of what of an atom?
The volume
How are electrons held?
The electrons closest to the nucleus is held tightly but the valence electrons are pretty lose
Which electrons have the highest energy level and which has the lowest ones
The one’s farthest from the nucleus has the highest energy level, the one’s closer to nucleus have the lowest energy level
How many electrons can the 1’st, 2nd and 3rd energy level hold
1st = 2 2nd = 8 3rd = 8
What determines how many valence energy levels an atom of an element has?
The number which horizontal row the element is in
What subatomic particle determines what element it is
The protons, if the proton numbers of an element change, then it’s a different element now
What is the atomic molar mass?
Average mass of an element’s isotopes aka. the atomic mass (g/mol)
What are isotopes?
Having different numbers of neutrons of the same element therefore the mass changes
How do you find out what isotope an element is?
Atomic Mass - Protons = Neutrons
Protons + Neutrons = Isotope/Atomic Mass
What does ionization mean?
The process of an atom gaining or losing electrons; results in metals & non-metals forming compounds
What are the 2 ions called and how are they formed?
A cation (positive ion) forms when metals lose electrons A anion (negative ion) forms when a non-metal gains ions
When do most ion formations take place?
When a metal and non-metal forms an ionic compound
In chemistry being more stable = ?
Less reactive
When are atoms most stable & unreactive?
When they have their valence/outer energy levels filled with 8 electrons
What are valence electrons and what is valency
Valence electrons are the electrons in the outermost shell and valency is the tendency to gain or lose those valence electrons
What is the valence number?
The amount of electrons an atom can gain or lose to combine with other elements
What does the octet rule state?
The octet rule states that atoms tend to lose, gain or shar electrons as to have 8 electrons in their valence energy level
Why do atoms lose or gain electrons?
They do that so they can have the same number of electrons as the nearest noble gas
What are the 3 exceptions to the octet rule?
H, Li, Beryllium because their nearest noble gas has only 2 valence electrons so they also only need 2
Every time an electron is lost………..
The nucleus holds onto the rest of it’s electrons more tightly
What are multivalent elements?
Multivalent elements are mostly metals and they are metals that can stably form more than one charge for ions
What is a formula unit?
The ratio of ions in a formula; - the smallest amount of a substance with the composition shown by a chemical formula
What must you do when formulating and naming ionic compounds?
- Put the cation 1st and anion 2nd
- Put -ide at the end of the anion
- Criss Cross the ion charges of the cation & anion
- You must reduce the ratio to the smallest multiple
How does the lowest common multiple method work?
Find the lowest common multiple for charges of both elements and then divide the multiple by the ion charge to get the formula
When do you have to show roman numerals?
When you’re naming an ionic compound and only if the element has more than 1 charge shown on the table
Tip: use the subscript of the anion to find the charge of the cation
What are polyatomic ions?
Ions made up of several non-metallic atoms combined
What charges are polyatomic ions?
All the polyatomic ions are negative except for ammonium
What are the 3 rules for naming and formulating polyatomic ions?
- Put cation first and anion 2nd; Note their ion charges and make a ratio
- Make the charge of the polyatomic ion the cation’s subscript and make the cation’s charge the polyatomic ion’s subscript
- Put brackets around the polyatomic ion if you need more than 1 of it
What are the rules for naming polyatomic ions with oxygen?
- The 2 most common suffixes in polyatomic ions are -ate & -ite
- -ate means more oxygen atoms (3-4)
- -ite means less oxygen atoms (1-2)
How does a molecule form?
When two or more non-metallic atoms bond together
Do molecular compounds have to have different elements?
No, they can be made up of the same element atoms too
What element atoms occur naturally as a pair in nature and what are they called?
They’re called diatomic molecules and they are:
I,H,N,Br,O,Cl,F
What are the 2 polyatomic molecules and how many atoms do they have?
Phosphorus with 4
Sulfur with 8
What are the rules for formulating and naming molecular compounds?
- Use prefixes
- Do not use mono on the first anion
- Name the 2nd anion with -ide at the end
What are the prefixes for molecular compounds upto 10?
Mono, Di, Tri, Tetra, Penta, Hexa, Hepta, Octa, Nona, Deca
What is the difference between Covalent & Ionic bonds?
Covalent bonds are formed by molecular compounds bonding and they share electrons
Ionic bonds are formed by ionic compounds bonding; Cations give/lose electrons to become stable
Anions take/receive electrons to become stable
Which element is unique and has been give simpler names?
Hydrogen
Name the 13 formulas you need to memorize
- Water = H20 (l)
- Hydrogen peroxide = H202 (l)
- Hydrogen Sulfide = H2S (g)
- Ammonia = NH3 (g)
- Methane = CH4 (g)
- Ethane = C2H6 (g)
- Propane = C3H8 (g)
- Butane = C4H10 (g)
- Methanol = CH3OH (l)
- Ethanol = C2H5OH (l)
- Sucrose = C12H22O11 (s)
- Glucose = C6H12O6 (s)
- Alcohol = CH3 CH2 OH (l)
What is a definite give away that a substance is an ionic compound?
If the formula begins with a cation or Ammonium (NH4)
What are the 5 ionic properties?
- Solids at room temp
- High melting/boiling point
- Crystalline solids and will retain shape when broken
- Soluble to some extent
- Only ionic compounds dissolved in water are conductive due to the ion attraction of water’s polarity
What are the 5 molecular properties?
- Low melting/boiling point
- Can be solids, liquids or gases at 25C
- Crystals will crumble easily when broken
- Only some are soluble
- They do not conduct electricity
What is a precipitate & precipitation?
When ionic solutions are mixed; A solid with low solubility that forms a solution
Precipitation is the process involved in forming a precipitate
Compounds containing ions from which group is most soluble?
Group 1 alkaline metals
Can molecular compounds form crystals?
Yes but they break easily
Why are the melting points of molecular compounds low?
Because while each individual molecule has a strong bond, the bonds between molecules aren’t strong
Why are ionic compounds in crystal lattices?
The attractions between cations & anions are so strong in an ionic compound that the ions are held tightly in an organized crystal lattice
What does IUPAC stand for?
The international union of Pure and Applied Chemistry
What do water molecules have?
They have a positive (hydrogen being slightly positive) end and a negative (oxygen being slightly negative)end making water polar
Why is water polar?
Because of it’s bend shape and the uneven sharing of electrons in a covalent bond
What is a hydrogen bond?
The force between the negative end of 1 water molecule to the positive end of another water molecule
What does the polarity of water cause it to do?
- Water is more dense than ice
- Have high boiling & melting points
- large capacity to absorb heat without large changes in temp
What are the 5 properties of acids
- Acids have a sour taste
- Not slippery
- Reacts with metals to form hydrogen gas
- Litmus paper turns red
- Conducts electricity
What are the 5 properties of bases
- Bases have a bitter taste
- Slippery
- Does not react/attack metals
- Litmus paper turns blue
- Conducts electricity
What does disassociate mean?
separate into ions; acids and bases do that when dissolved
What does an acid contain and what does a base contain?
An acid contains hydrogen ions and a base contains OH (hydroxide ions)
What is a buffer:
A solution containing an acid or base that tends to maintain a constant hydrogen concentration
How do you know for sure if it’s an acid?
It it starts with H, ends with COOH and is dissolved in water; has (aq)
How do you name acids with the IUPAC system?
- Place aqueous first
2. Name it like an ionic compound
What indicates a solution is a base?
Compound with high solubility
Has an OH ion at the right of formula and has a metal or ammonium ion in the beginning
What does neutralization do?
When acids & bases react together, both properties disappear and it ends up producing water and a compound called a salt
