chem Flashcards
what are Elements ?
They are a single type of atom
what are compounds ?
2 or more elements that are chemically bonded
where are electrons located and what is the mass and charge of it ?
on outer shell –> mass = 1/2000 , charge = -1
where are protons located and what is the mass and charge of it ?
in the middle (nucleus) –> mass = 1 , charge = +1
where are neutrons located and what is the mass and charge of it ?
in the middle (nucleus) –> mass = 1 , charge = 0
How can we tell if the number is an atomic number and what does it represent ?
smaller number = protons and electrons (not added)
How can we tell if the number is an mass number and what does it represent ?
larger number = protons + neutrons
who discovered protons ?
Rutherford
who discovered neutrons ?
James Chadwick
who discovered nucleus ?
Rutherford
who discovered electrons ?
J.J. Thomson
who discovered the current model we know today ?
Bohr
Tell me 3 things about Dmitri Mendeleev’s table and what has changed ?
- was sorted by mass and similar patterns
- left gaps
- he predicted properties
(but now we arrange it in electronic arrangements – subtle difference)
what it the formula for
- Carbon dioxide
- water
- oxygen gas
- hydrogen gas
- nitrogen gas
- ammonia
- hydrochloric acid
- sulfuric acid
- CO2
- H2O
- O2
- H2
- N2
- NH3
- HCI
- H2SO4
Tell me 5 things about Halogens.
- In group 7
- Non metals
- Only need to gain one electron so very reactive
- Most reactive on top and least reactive in bottom
- Low boil on top and high boil on bottom
Tell me 4 things about alkali metals.
– group 1
- least reactive on the top but most reactive in the bottom
- high melting point on the top but low melting point in the bottom
- Soft grey metal – need to be kept in oil so it doesn’t react with oxygen or water in the air
Tell me 3 things about Nobel gases.
- group 8/0
- Has full outer shell
- meaning it’s Unreactive
what does the state symbol (Aq) stand for ?
aqueous
From it’s structure why can pure metals conduct electricity and can conduct heat ?
Pure Metals are made up of positive atoms in a sea of delocalized electrons which are free to move meaning the metals can conduct electricity and be a really good source of conducting heat.
Are pure metals soft or hard ? why ?
Pure metal has layers that can slide across each other and because of this they are soft.
Are alloys soft or hard ? why ?
Alloys either have no layer or distorted layer and they cannot slide meaning they are hard.
Explain the structure of an alloy ?
An alloy has the same things as a pure metal (positive atoms in a sea of delocalized electrons) but it also includes another metal or e.g. carbon that is alloyed with.
what’s the molecule formula for Octane ?
C8H18
what’s the molecule formula for hexane ?
C6H14
what’s the molecule formula for methane ?
CH4
what’s the molecule formula for Decane ?
C10H22
what’s the molecule formula for heptane ?
C7H16
what’s the molecule formula for propane ?
C3H8
what’s the molecule formula for ethane ?
C2H6
what’s the molecule formula for pentane ?
C5H12
what’s the molecule formula for nonane ?
C9H20
what’s the molecule formula for butane ?
C4H10
what are the properties of transition metals ?
- good conductor
- shiny
- hard
what are the uses of transition metals ?
- jewellery
- wires
- sculptures
what are the colours of transition metals ?
- copper = blue
- iron (II) = light green
- iron (III) = orangey brown (rust)
- cobalt = deep rich blue
why do group 1 elements become more reactive as you go down the line ?
As you move down the group the outer electrons is further away from the nucleus so it is less strongly attracted to the nucleus and is more easily lost .
Define what is meant by the term isotope.
Atoms of the same element that have different numbers of neutrons.
Define relative atomic mass.
The average value that takes into account the abundance of the isotopes of the element.
