Topic 1 Flashcards
What’s the symbol, relative mass and relative charge of a proton?
p
1
+1
What’s the symbol, relative mass and relative charge of a neutron?
n
1
0
What’s the symbol, relative mass and relative charge of a electron?
e
1/1835
-1
What is nucleon?
Proton + neutron
What are vertical and horizontal rows called on the periodic table?
Groups and periods
What do elements in the same group have in common?
Same number of electrons in the outer shell
What do elements in the same period have in common?
The same number of shells
What is the electron arrangement?
2,8,8,18
What must an element have to be stable?
A full outer shell
What are stable elements like?
They’re unreactive and won’t gain or lose electrons which are needed for elements to react
What do ion charges correspond to?
The group number/ eg beryllium in g2 so its Be^+2
How can you tell if ion charge is positive or negative?
From group 5 they are negative ions
What are positive ions called?
They’re just called “element name” ion eg Na^+ is sodium ion
What are negative ions called?
Monoatomic ions end in ‘ide’ eg O^2- is oxide. Polyatomic ions (more than one) with oxygen end in ‘ate’
What are isotopes?
Atoms with the same number of protons but different number of neutrons
What is an element?
Pure substances made up of only one type of atom
What are compounds?
Pure substances that are formed when two or more elements chemically combine
What are mixtures?
Not pure substances. They contain more than one substance that aren’t bonded together
Give three examples of an element, compound and mixture
Element- Hydrogen, oxygen, nitrogen
Compound- H2O (water), CO2 (carbon dioxide), NaCl (table salt)
Mixture- saltwater, milk, cement
What are the characteristics of a compound?
- Single substance
- Composition is always the same
- Components can be separated by one or more chemical reaction
- When the new substance is formed it involved chemical change
- The properties are very different to those of component elements
What are the characteristics of a mixture?
- Contain 2 or more substances
- Composition can vary
- Components may be separated easily by physical means
- The properties are very different to those of component elements
- No chemical change can take place when this substance is formed
What are the properties of metals?
- Malleable
- Ductile
- High heat and electricity conductivity
- Usually, high boiling and melting points
- Mostly solid at room temp
- Shiny
What are the properties of non-metals?
- Can be any state
- Soft
- Brittle
- Dull
- Usually low melting and boiling points
- Low heat and electricity conductivity
What are alloys?
A mixture of metals. The atoms aren’t chemically bonded
Why are alloys used instead of regular metals?
Because their properties are different like how steel is more resistant to corrosion than iron
Across the period what do elements become less?
Metallic
What are the periodic table trends?
Group 1: All metallic solids
Group 2: All metallic, but less reaction than G1
Group 4: Non metals/metals usually solid
Group 6-8: All non-metals usually gases
What happens when you go down group 1 and 2?
Reactivity increases but melting and boiling points decrease
What happens when you go down group 7?
Reactivity decreases and substance changes from gas to solid
What is chromatography?
A technique used to separate mixtures of soluble solid materials so they can be identified
What is paper chromatography?
A simple experiment used to separate colored components
What is Rf?
Retention factor. The larger it is, the more soluble the sample is
What is the mobile phase in chromatography?
When the solvent moves up the paper chromatogram to separate the sample
What is the stationary phase in chromatography?
The paper when the solvent hasn’t moved up
What is the formula for Rf?
Distance travelled by substance (from baseline)/ distance travelled by solvent (solvent front)
- Measured to the cen3tre of spots
What makes colourless objects visible on a chromatogram?
A locating agent which reacts with the substance to form a coloured product
Why do you draw the baseline in pencil not with pen?
Because the ink could get separated in the experiment and interfere with the sample
What are pure substances?
Substances with a definite composition, properties remain the same, and defined properties, the boiling point, melting point and density won’t change
How can purity be monitored?
- Melting point
- Boiling point
- Chromatography
What’s the difference between a pure and impure substances melting point/boiling point?
Pure substances have a sharp melting/boiling point whil impure substances will melt/boil over a range of temperatures
What’s the difference between a pure and impure substances chromatography?
Pure substances will produce only one well defined spot while impure substances produce several spots
What is the liquid that can dissolve the solid?
Solvent
What is it called if a solid can dissolve in a liquid?
Soluble
What is a mixture of a soluble solid and a liquid?
Solution
What is a solid that can dissolve in a liquid called?
Solute
What is it called if a solid is unable to dissolve in a liquid?
Insoluble
Explain, in terms of electrons why Group 1 elements react similarly?
Because they all have the same number of valence electrons and the valence shell is the only part that participates in the reactions
What happens when sodium is placed in water?
Moves quickly over surface of water, melts into a silvery ball, eventually disappears
What does filtration separate?
Solid/liquid (insoluble)
What does evaporation separate?
Solid/liquid (soluble solid)
What does crystallising separate?
Solid/Liquid (soluble solid)
What does distillation separate?
Solid/Liquid (soluble)
What does separation funnel separate?
Liquid/liquid (immiscible)
What are the properties of solids?
Packed closely together, regular arrangement, strong attraction between particles, can’t move freely but can vibrate, fixed shape, fixed volume, can’t be compressed, can’t diffuse
What are the properties of liquids?
Particles are still touching, irregular arrangement, forces of attraction are less strong than solids, can freely move and slide, acquires shape of container, fixed volume, can’t be compressed, slowly diffuse
What are the properties of gases?
Spread out, irregular, no forces of attraction between particles, irregular arrangement, random movement, no fixed shape, not fixed volume, can be compressed, diffuse quickly
What happens to energy particles when they have more thermal energy?
More kinetic energy and the increased energy causes forces of attraction (bonds) to break allowing state changes to occur
What is the melting point?
Temperature when a substance begins to change from solid to liquid
What is the boiling point?
Temperature when a substance begins to change from liquid to gas
What do heating and cooling curves show?
The temperature of a substance as it heated/cooled over time
What is pressure?
The force exerted by gas molecules colliding with surfaces of objects or other particles
What’s the formula of pressure?
Force/area
What does increasing the volume do to the pressure of a gas?
Decreases it
What does increasing the temperature in a set volume do to the pressure of a gas?
Increases it
What does increasing the number of molecules in a set volume do to the pressure of a gas?
Increases it
Potassium reacts violently with water. Complete the word equation.
Potassium + water-> hydrogen + potassium hydroxide
What is diffusion?
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration until they’ve reached equilibrium
What diffuses slower between liquid and gases and why?
Particles in liquids have less energy than gases which is why they diffuse slower
Do particles with a larger mass or smaller mass diffuse faster?
Smaller mass
Does decreasing temperature slow down or speed up diffusion? Why?
Slow down because lower temperature means the molecules have lower energy meaning they diffuse slower
A teacher placed a small amount of liquid bromine in the bottom of a sealed gas jar of air. After two minutes red-brown fumes were seen just above the liquid surface. After one hour, the red-brown colour had spread completely throughout the gas jar. Use the kinetic particle model of matter to explain these observations (3).
Any three of
- Bromine evaporates/liquid evaporates
- More energetic particles change from liquid to vapor to gas
- Diffusion
- Random movement of particles
- Collision of bromine and air particles
Why do isotopes have the same properties?
Because they have the same amount of electrons in the outer shell
Why do atoms with more electron shells have higher energy levels?
Because the valence electrons are further away from the nucleus
What are the physical properties of group 1 metals?
Soft, grey, shiny when cut but tarnishes, relatively low melting point, boiling point and density
Briefly explain the process of fractional distillation to separate a mixture of the liquids methanol, ethanol and propanol
- Heat is applied and the liquid with the lowest boiling point evaporates and condenses into a beaker.
- If other liquids evaporate by chance, they condense in the fractionating column back into the flask.
- The temperature is altered to repeat the process for the second liquid.
- The three liquids are separated based on differing boiling points with the third remaining in the flask.
