atoms molecules etcccccc Flashcards
what is the periodic table of the elements (the periodic table)?
an arrangement of all known chemical elements in order of atomic number that groups elements with common characteristics in the same area of the table.
What are physical properties and chemical properties?
physical properties describe a substance’s characteristics observable without changing its chemical composition (e.g. colour), while chemical properties describe how a substance reacts or changes into other substances (like reactivity).
What is a molecule?
a molecule is a group of two or more ATOMS held together by chemical bonds.
What is a compound?
a compound is a substance made up of two or more DIFFERENT ELEMENTS chemically bonded together.
What are groups in chemistry?
a group, in chemistry, is a column in the periodic table of the chemical elements. In a group, the chemical elements have atoms with identical electron counts and identical vacancy counts. they therefore have similar chemical properties.
What is a chemical bond (bond)?
an attraction between atoms or molecules that enables the formation of chemical compounds.
What is a chemical formula?
a series of chemical symbols showing the number of atoms of each element in a compound.
What are chemical periods (periods)?
a period on the periodic table is a row of chemical elements. all elements in a row have the same number of electron shells.
What are reactants?
in a chemical reaction, reactants are the starting substances that undergo a change to form new substances called products.
What are products? (kinda answered in what are reactants)?
products are the species formed from chemical reactions.
What is an element?
elements are pure substances made up of only one type of atom. e.g. lithium
What is an exothermic reaction?
exothermic reactions are chemical reactions which release energy from the chemicals into the surroundings. they can cause a temperature increase, combustion, oxidation and neutralisation reactions are all examples.
What is an endothermic reaction?
these are reactions that take in energy from the surroundings. these can cause a temperature decrease, thermal decomposition is an example.
What are atoms?
the smallest part of an element that can exist.
What is a chemical symbol?
a chemical symbol, also called an element symbol, is a letter or pair of letters used to represent a chemical element.
What are metals and non-metals?
a metal is defined as a substance with high electrical and thermal conductivity. a non-metal is a chemical element that lacks the characteristic properties of metals, typically being poor conductors of heat and electricity.
What is a mixture?
a mixture is a physical combination of two or more substances where no chemical reaction occurs, meaning the individual constituents retain their unique properties and can be separated by physical means. the substances can be elements, compounds or both.
What is an atomic number?
the number of protons in the nucleus of the atom. also called the proton number.
What is reactivity?
the tendency of a substance to undergo a chemical reaction.
An —————- is a substance that cannot be broken down into other ————–. The smallest part of an —————— that can exist is an —————.
clue the answers for 1 and 3 are the same.
- element
- substances
- element
- atom
How are the symbols for any element arranged on the periodic table? Is it either (from top to bottom),
a)
atomic mass
element name
element symbol
atomic number
or
b)
atomic mass
element symbol
element name
atomic number?
b)
Fill in the gaps on these facts about compounds.
COMPOUNDS
the different ————– are —————- joined together
the ———- has different properties to the ————– it is made from
the elements can only be separated using ———— reactions
you —————- vary the amount of each ————-. So, the compound ————- has one oxygen atom and two —————- atoms per molecule.
clue looks like minnie mouse
1) elements
2) chemically
3) substance
4) elements
5) chemical
6) cannot (accept anything along this)
7) element
8) water
9 hydrogen
Fill in the gaps on these facts about mixtures.
MIXTURES
the different ———– are ———- chemically joined together
each substance keeps its ——– properties
each substance can be ———— separated using separating techniques like —————–, distillation, —————- and chromatography
you ———— vary the amount of each —————-. So, you can add a teaspoon of salt to water, and it ————— still be a ———————- of salt ————–.
1) substances
2) not
3) own
4) easily
5) filtration / evaporation
6) filtration / evaporation
7) can
8) substance
9) would
10) mixture
11) water
What are some features which redeem an alkali metal?
ALKALI METALS ARE GROUP 1 IN THE PERIODIC TABLE
Alkali metals are “redeemed” by their unique properties, including being soft, highly reactive, having low densities and melting points, and readily forming alkaline solutions when reacting with water. the elements become more reactive as you go down group one.
Fill in the gaps
When the group ———- metals react in water they produce a ——— hydroxide and —————— gas. e.g. lithium + water (to) lithium hydroxide + hydrogen
clue hydroxide sounds like…
1) 1
2) metal
3) hydrogen
GROUP TWO, ALKALI EARTH METALS
Fill in the gaps
Group two metals are ——– but less reactive than group ———– elements.
Group two metals react with ——— to produce a (type of ) salt and ————–.
The name of the ———- depends on the acid used.
Hydrochloric acid - chloride
Sulfuric acid - sulfate
Nitric acid - nitrate
e.g.
magnesium + hydrochloric acid-magnesium chloride + hydrogen
1) reactive
2) 1
3) acids
4) hydrogen
5) salt
True or False?
Are alkali earth metals more reactive than alkali metals?
FALSE
The HALOGENS - GROUP 7
fill in the gaps
Group —– elements become ————- reactive when you move down the ———. This can be shown as a —————— reaction.
1) 7
2) less
3) group
4) displacement
THE NOBLE GASES- GROUP 0
fill in the gaps
Group —— elements are ———— reactive. This is because the ——– have ——— outer ————.
1) 0
2) not
3) atoms
4) full
5) shells
What is the element symbol for each of these?
GROUP 1
lithium-
sodium-
potassium-
GROUP 2
beryllium-
magnesium-
calcium-
GROUP 3
boron-
aluminium-
gallium-
GROUP 4
carbon-
silicon-
germanium-
GROUP 5
nitrogen-
phosphorus-
arsenic-
GROUP 6
oxygen-
sulfur-
selenium-
GROUP 7
fluorine-
chlorine-
bromine-
GROUP 8
helium-
neon-
argon-
1)
a) Li
b) Na
c) k
2)
a) Be
b) Mg
c) Ca
3)
a) B
b) Al
c) Ga
4)
a) C
b) Si
c) Ge
5)
a) N
b) P
c) As
6)
a) O
b) S
c) S
7)
a) F
b) Cl
c) Br
8)
a) He
b) Ne
c) Ar
What is the conservation of mass?
The total mass of the products in a chemical reaction will be the same as the total mass of the reactant.
What is the structure of the atom?
Atoms consist of a central nucleus containing protons (positive charge) and neutrons (no charge), surrounded by negatively charged electrons in shells or orbitals
What elements and compounds make up air?
Air, or Earth’s atmosphere, is a mixture of gases, primarily composed of nitrogen (78%), oxygen (21%), with smaller amounts of argon, carbon dioxide, and trace gases
How does air pressure react in containers when balanced vs unbalanced?
When air pressure inside and outside a container is balanced, the container remains stable, but when unbalanced, the stronger force will cause the container to deform or collapse.
What are the different tests for oxygen, carbon dioxide, hydrogen and chlorine?
Hydrogen (H2) causes a lit splint to burn with a ‘squeaky pop’.
Oxygen (O2) relights a glowing splint.
Carbon dioxide (CO2) turns limewater cloudy.
Chlorine (Cl2) bleaches damp blue litmus paper white.
How do you heat substances carefully in a crucible?
These are some things you can do/say:
Preparation:
Crucible: Ensure the crucible is clean and dry before use.
Support: Place the crucible on a pipe clay triangle, which is in turn placed on a tripod, to allow for even heat distribution and prevent direct contact with the heat source.
Heat Source: Use a Bunsen burner or other heat source, starting with a low flame and gradually increasing the heat.
Heating:
Slow and Steady: Heat the crucible slowly and evenly to avoid cracking or damage, especially when heating from a cold state.
Observation: Observe the reaction or decomposition of the substance, and adjust the heat as needed.
Lid: If using a lid, remove it carefully with tongs to inspect the contents, and always view the open crucible from the side, not directly above.
Cooling:
Gradual Cooling: Allow the crucible and its contents to cool gradually to prevent cracking or damage.
Avoid Direct Contact: Do not place the hot crucible on a cold surface, as this can cause rapid temperature changes and breakage.
Cooling Method: Allow the crucible to cool on the tripod or a heat-resistant surface.
Safety:
Safety Glasses: Always wear safety glasses when working with crucibles and heat sources.
Tongs: Use tongs to handle hot crucibles.
Moisture: Ensure that any residual moisture is removed from the crucible and/or furnace refractories before use.
Volatile Substances: Be careful when handling volatile substances and ensure proper ventilation.
How to balance equations?
A balanced equation gives more information about a chemical reaction because it gives the symbols and formulae of the substances involved.
e.g.
WRONG
Cu + O₂ →CuO
CORRECT
2Cu + O₂ →2CuO
How do you investigate the combustion of magnesium with oxygen?
1) Cut a piece of magnesium about 10–15 cm long. If it is looking tarnished or black then clean it using the emery paper. 2) Twist it into a loose coil.
3) Weigh the crucible with the lid (mass 1) and then the magnesium inside the crucible with the lid (mass 2).
4) Set up the Bunsen burner on the heat resistant mat with the tripod. Place the pipe clay triangle over the tripod in a Star of David formation, ensuring that it is secure. Place the crucible containing the magnesium in the pipe clay triangle and put the lid on.
5) Light the Bunsen burner and begin to heat the crucible. It is best to start with a gentle blue flame, but you will need to use a roaring flame (with the air hole fully open) to get the reaction to go.
6) Once the crucible is hot, gently lift the lid with the tongs a little to allow some oxygen to get in. You may see the magnesium begin to flare up. If the lid is off for too long then the magnesium oxide product will begin to escape. Don’t let this happen.
7) Keep heating and lifting the lid until you see no further reaction. 8) At this point, remove the lid and heat for another couple of minutes. Replace the lid if it appears that you are losing some product.
9) Turn off the Bunsen burner and allow the apparatus to cool.
10) Re-weigh the crucible with lid containing the product (mass 3).
11) Heat the crucible again for a couple of minutes and once again allow it to cool. Repeat this step until the mass readings are consistent. This is known as heating to constant mass.
NOTE; WEAR EYE PROTECTION AND HAVE LONG HAIR TIED BACK
The effect of increasing air pressure inside of a can…
Increasing air pressure inside a can, especially when combined with a rapid temperature drop, can cause the can to crush because the higher external air pressure overwhelms the reduced internal pressure, leading to an inward force that the can can’t withstand.
Measuring the volume of oxygen inside of a container?
(TEALIGHT) (GLOWING SPLINT)
TEALIGHT
To measure the volume of oxygen inside a tea light gas jar, you can use a simple experiment: light a candle, place it in a jar, and observe the water level rise as the candle consumes the oxygen, demonstrating the volume of oxygen originally present.
Materials:
A tealight candle, A clear glass jar or container, A tray or dish, Water, and A ruler or measuring tape (optional).
Procedure:
1. Prepare the setup:
Fill the tray with water, ensuring the jar can be placed upside down in the water without spilling.
2. Light the candle:
Light the tealight candle and place it in the center of the tray.
3. Cover the candle:
Carefully place the jar upside down over the burning candle, ensuring a good seal around the rim of the jar.
4. Observe the water level:
Watch as the candle burns. You’ll notice the candle flame will eventually go out, and the water level will rise inside the jar.
5. Measure the water level:
After the candle goes out, measure the amount of water that has risen into the jar using a ruler or measuring tape.
GLOWING SPLINT
To test for oxygen using a glowing splint, a splint (like a small piece of wood) is extinguished to leave only glowing embers, and then introduced into a container suspected to contain oxygen; if oxygen is present, the glowing splint will relight.
Here’s a more detailed explanation:
The Glowing Splint Test:
Light a splint (a small piece of wood) and then extinguish the flame, leaving only glowing embers.
Carefully introduce the glowing splint into the container suspected to hold oxygen.
If oxygen is present, the glowing splint will relight and burn brightly.
If the gas is carbon dioxide, the splint will go out.
Why it works:
Oxygen is a supporter of combustion, meaning it’s necessary for flames to burn.
When the glowing splint is introduced into a container of oxygen, the oxygen supports the combustion of the splint, causing it to relight and burn.
High levels of oxygen or carbon dioxide can be detected with a glowing splint. If a glowing splint is placed into a volume of oxygen gas, it will reignite. If the splint is placed into a volume of carbon dioxide, it will be extinguished.
How to identify the type of gas produced following chemical reactions between substances?
To identify the type of gas produced in a chemical reaction, you can use specific tests, such as the limewater test for carbon dioxide, the glowing splint test for oxygen, and the squeaky pop test for hydrogen.
what is oxidation?
reaction of other elements with oxygen
What is combustion?
burning fuel in oxygen.
What is thermal decomposition?
When a substance is broken down into 2 or more products by heat. It must be by one reactant.
What is reactivity series?
list of metals in order of reactivity, from most reactive at the top to least reactive at the bottom.
What is displacement?
A more reactive metal will displace a less reactive metal from the compound.
What is a catalyst?
A substance that increases the rate of a reaction but is not itself used up.
What is a polymer?
Long chain molecules made up of many monomers.
What is fuel?
Contain hydrocarbons- compounds containing hydrogen and carbon atoms only.
What is activation energy?
The minimum amount of energy that colliding particles must have for them to react.
What are displacement reactions?
displacement reactions involve a metal and a compound of a different metal. In displacement reactions, a more reactive metal will displace a less reactive metal from its compound.
e.g. magnesium + copper sulphate → magnesium sulphate + copper
explanation: Magnesium is more reactive than copper, so it displaces (pushes out) the copper within the compound.
COMPLETE combustion VS INCOMPLETE combustion:
COMPLETE
coal, oil and gas are all furls. they contain hydrocarbons (compounds of hydrogen and carbon atoms only). When these fuels burn, it reacts with oxygen in the air to produce carbon dioxide and water vapour.
e.g. Fuel + Oxygen → Carbon dioxide + Water
INCOMPLETE
if there is not enough oxygen in the air for complete combustion, incomplete combustion will happen instead. This time either carbon monoxide is produced (a toxic gas which can lead to death) or carbon is produced ( appears as soot and smoke which can cause breathing problems).
e.g. Fuel + Oxygen → Carbon Monoxide + Water (H2O)
Fuel + Oxygen → Carbon + Water
Which gases arise from different chemical reactions?
Which gases arise from different chemical reactions?
Many chemical reactions produce gases as products, including carbon dioxide (CO2), hydrogen sulfide (H2S), ammonia (NH3), and sulfur dioxide (SO2), among others.
Carbon Dioxide (CO2):
Combustion: Burning fuels like wood, natural gas, and coal produces CO2.
Acid-Base Reactions: When acids react with carbonates (like limestone or baking soda), CO2 is released.
Respiration: Animals and humans exhale CO2 as a byproduct of cellular respiration.
Cement Manufacturing: The production of cement involves the decomposition of limestone, releasing CO2.
Hydrogen Sulfide (H2S):
Decomposition of Organic Matter: H2S is a common product of the decomposition of organic matter in anaerobic (oxygen-deprived) environments, such as in swamps, sewers, and some types of soil.
Volcanic Activity: H2S is also released from volcanic vents.
Ammonia (NH3):
Decomposition of Nitrogen-Containing Compounds: Ammonia can be produced when nitrogen-containing organic matter decomposes.
Industrial Processes: Ammonia is produced industrially through the Haber-Bosch process, which combines nitrogen and hydrogen.
Sulfur Dioxide (SO2):
Combustion of Sulfur-Containing Fuels: SO2 is released when fuels containing sulfur (like coal) are burned.
Volcanic Activity: SO2 is also a common product of volcanic eruptions.
Hydrogen (H2):
Reaction of Metals with Acids: Certain metals, like magnesium or zinc, react with acids (like hydrochloric acid) to produce hydrogen gas.
Oxygen (O2):
Decomposition of Certain Compounds: Some chemical reactions, like the decomposition of hydrogen peroxide (H2O2), produce oxygen gas.
Photosynthesis: Plants produce oxygen as a byproduct of photosynthesis.
Methane (CH4):
Decomposition of Organic Matter: Methane is produced when organic matter decomposes in anaerobic conditions, such as in wetlands and landfills.
Fossil Fuel Production: Methane is a component of natural gas, a fossil fuel.
Different chemical reactions which lead to hydrogen
Lithium + Water - lithium hydroxide + hydrogen
Magnesium + Hydrochloric acid - magnesium chloride + hydrogen
Magnesium + Sulfuric Acid - magnesium sulfate + hydrogen
Magnesium + Nitric acid - magnesium nitrate + hydrogen
Which different chemical reactions lead to carbon dioxide (or carbon) being produced?
Fuel + oxygen - carbon dioxide + water
Fuel + Oxygen - carbon monoxide + water
Fuel + Oxygen - carbon + water
Write the oxidation reaction in the correct chemical symbols :
Copper + oxygen- copper oxide
2Cu+O₂ - 2CuO
What is copper carbonate comprised of?
Copper Oxide + Carbon Dioxide
Copper carbonate is green, copper oxide is black. We can test for carbon dioxide by using limewater. Limewater is colourless, but turns cloudy when carbon dioxide is bubbled through it.
Write Lithium + Water - Lithium Hydroxide + Hydrogen in symbols.
2Li(s) + 2H₂O(l) → 2LiOH(aq) + H₂(g).
Here’s a breakdown:
2Li(s): Represents 2 moles of solid lithium.
2H₂O(l): Represents 2 moles of liquid water.
→: Indicates “reacts to form” or “yields”.
2LiOH(aq): Represents 2 moles of aqueous lithium hydroxide.
+: Indicates “plus” or “and”.
H₂(g): Represents 1 mole of gaseous hydrogen.
What is chemical reactivity?
A substance’s tendency to undergo a chemical reaction.
CHOOSE FROM: Br2, He, H2, H2O, O2, Cl2, l2, NH3, N2, CO2, HF, F2, CH4, HBr, C2H4, Ne
1) Choose from the list, write down the formula of any elements.
2) Any substances that contain 2 atoms?
3) Any substances that contain 3 atoms?
4) Any substances that contain 4 atoms?
5) Any substances that contain 5 atoms?
6) Any substances that contain 6 atoms?
7) ARE ALL SUBSTANCES WITH TWO ATOMS COMPOUNDS?
1) H2
2) Br2
3) CO2
4) NH3
5) CH4
6) C2H4
7) No.
