atoms molecules etc

Question 1

what is the periodic table of the elements (the periodic table)?

Answer 1

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.

Question 2

What are physical properties and chemical properties?

Answer 2

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).

Question 3

What is a molecule?

Answer 3

a molecule is a group of two or more ATOMS held together by chemical bonds.

Question 4

What is a compound?

Answer 4

a compound is a substance made up of two or more DIFFERENT ELEMENTS chemically bonded together.

Question 5

What are groups in chemistry?

Answer 5

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.

Question 6

What is a chemical bond (bond)?

Answer 6

an attraction between atoms or molecules that enables the formation of chemical compounds.

Question 7

What is a chemical formula?

Answer 7

a series of chemical symbols showing the number of atoms of each element in a compound.

Question 8

What are chemical periods (periods)?

Answer 8

a period on the periodic table is a row of chemical elements. all elements in a row have the same number of electron shells.

Question 9

What are reactants?

Answer 9

in a chemical reaction, reactants are the starting substances that undergo a change to form new substances called products.

Question 10

What are products? (kinda answered in what are reactants)?

Answer 10

products are the species formed from chemical reactions.

Question 11

What is an element?

Answer 11

elements are pure substances made up of only one type of atom. e.g. lithium

Question 12

What is an exothermic reaction?

Answer 12

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.

Question 13

What is an endothermic reaction?

Answer 13

these are reactions that take in energy from the surroundings. these can cause a temperature decrease, thermal decomposition is an example.

Question 14

What are atoms?

Answer 14

the smallest part of an element that can exist.

Question 15

What is a chemical symbol?

Answer 15

a chemical symbol, also called an element symbol, is a letter or pair of letters used to represent a chemical element.

Question 16

What are metals and non-metals?

Answer 16

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.

Question 17

What is a mixture?

Answer 17

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.

Question 18

What is an atomic number?

Answer 18

the number of protons in the nucleus of the atom. also called the proton number.

Question 19

What is reactivity?

Answer 19

the tendency of a substance to undergo a chemical reaction.

Question 20

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.

Answer 20

1. element
2. substances
3. element
4. atom

Question 21

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?

Answer 21

b)

Question 22

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

Answer 22

1) elements
2) chemically
3) substance
4) elements
5) chemical
6) cannot (accept anything along this)
7) element
8) water
9 hydrogen

Question 23

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 ————–.

Answer 23

1) substances
2) not
3) own
4) easily
5) filtration / evaporation
6) filtration / evaporation
7) can
8) substance
9) would
10) mixture
11) water

Question 24

What are some features which redeem an alkali metal?

ALKALI METALS ARE GROUP 1 IN THE PERIODIC TABLE

Answer 24

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.

Question 25

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...

Answer 25

1) 1 2) metal 3) hydrogen

Question 26

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

Answer 26

1) reactive 2) 1 3) acids 4) hydrogen 5) salt

Question 27

True or False? Are alkali earth metals more reactive than alkali metals?

Answer 27

FALSE

Question 28

The HALOGENS - GROUP 7 fill in the gaps Group ----- elements become ------------- reactive when you move down the ---------. This can be shown as a ------------------ reaction.

Answer 28

1) 7 2) less 3) group 4) displacement

Question 29

THE NOBLE GASES- GROUP 0 fill in the gaps Group ------ elements are ------------ reactive. This is because the -------- have --------- outer ------------.

Answer 29

1) 0 2) not 3) atoms 4) full 5) shells

Question 30

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-

Answer 30

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) Se 7) a) F b) Cl c) Br 8) a) He b) Ne c) Ar

Question 31

What is the conservation of mass?

Answer 31

The total mass of the products in a chemical reaction will be the same as the total mass of the reactant.

Question 32

What is the structure of the atom?

Answer 32

Atoms consist of a central nucleus containing protons (positive charge) and neutrons (no charge), surrounded by negatively charged electrons in shells or orbitals

Question 33

What elements and compounds make up air?

Answer 33

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

Question 34

How does air pressure react in containers when balanced vs unbalanced?

Answer 34

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.

Question 35

What are the different tests for oxygen, carbon dioxide, hydrogen and chlorine?

Answer 35

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 TO OXYGEN If oxygen is present in a test tube a glowing splint relights when it is held inside. HYDROGEN If hydrogen is present in a test tube a lit splint held near its mouth ignites with a squeaky pop CARBON DIOXIDE Limewater turns milky in the presence of carbon dioxide. is a solution of calcium hydroxide. If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white.

Question 36

How do you heat substances carefully in a crucible?

Answer 36

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.

Question 37

How to balance equations?

Answer 37

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

Question 38

How do you investigate the combustion of magnesium with oxygen?

Answer 38

1) Weigh and record the total mass of magnesium, crucible and lid, weigh the mass. 2) Heat the crucible and magnesium with the lid ON to start the reaction. 3) Once the crucible is hot, gently lift the lid with togs a little and allow some oxygen to get in. You may see the magnesium begin to flare up. If the lid is off for too long, some of the product will escape. 4) Heat strongly with the lid on for at least 5 mins, letting a bit of oxygen into the crucible until the sample no longer glows brightly when you lift the lid. 5) remove the lid and heat strongly for a further 5 mins. 6) allow the apparatus to cool and re - weigh the crucible, making note of the mass. Put the crucible on a heat proof mat to carry this to the balance. Beware of burns as this may still be hot. NOTE; WEAR EYE PROTECTION AND HAVE LONG HAIR TIED BACK

Question 39

The effect of increasing air pressure inside of a can...

Answer 39

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.

Question 40

Measuring the volume of oxygen inside of a container? (TEALIGHT)

Answer 40

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.

Question 41

How to identify the type of gas produced following chemical reactions between substances?

Answer 41

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.

Question 42

what is oxidation?

Answer 42

reaction of other elements with oxygen

Question 43

What is combustion?

Answer 43

burning fuel in oxygen.

Question 44

What is thermal decomposition?

Answer 44

When a substance is broken down into 2 or more products by heat. It must be by one reactant.

Question 45

What is reactivity series?

Answer 45

list of metals in order of reactivity, from most reactive at the top to least reactive at the bottom.

Question 46

What is displacement?

Answer 46

A more reactive metal will displace a less reactive metal from the compound.

Question 47

What is a catalyst?

Answer 47

A substance that increases the rate of a reaction but is not itself used up.

Question 48

What is a polymer?

Answer 48

Long chain molecules made up of many monomers.

Question 49

What is fuel?

Answer 49

Contain hydrocarbons- compounds containing hydrogen and carbon atoms only.

Question 50

What is activation energy?

Answer 50

The minimum amount of energy that colliding particles must have for them to react.

Question 51

What are displacement reactions?

Answer 51

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.

Question 52

COMPLETE combustion VS INCOMPLETE combustion:

Answer 52

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

Question 53

Which gases arise from different chemical reactions?

Question 54

Which gases arise from different chemical reactions?

Answer 54

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.

Question 55

Different chemical reactions which lead to hydrogen

Answer 55

Lithium + Water - lithium hydroxide + hydrogen Magnesium + Hydrochloric acid - magnesium chloride + hydrogen Magnesium + Sulfuric Acid - magnesium sulfate + hydrogen Magnesium + Nitric acid - magnesium nitrate + hydrogen

Question 56

Which different chemical reactions lead to carbon dioxide (or carbon) being produced?

Answer 56

Fuel + oxygen - carbon dioxide + water Fuel + Oxygen - carbon monoxide + water Fuel + Oxygen - carbon + water

Question 57

Write the oxidation reaction in the correct chemical symbols : Copper + oxygen- copper oxide

Answer 57

2Cu+O₂ - 2CuO

Question 58

What is copper carbonate comprised of?

Answer 58

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.

Question 59

Write Lithium + Water - Lithium Hydroxide + Hydrogen in symbols.

Answer 59

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.

Question 60

What is chemical reactivity?

Answer 60

A substance's tendency to undergo a chemical reaction.

Question 61

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?

Answer 61

1) H2 2) Br2 3) CO2 4) NH3 5) CH4 6) C2H4 7) No.

Question 62

what is the air made of?

Answer 62

Air is primarily a mixture of gases, mainly nitrogen (about 78%) and oxygen (about 21%). It also contains trace amounts of other gases like argon, carbon dioxide, and various other substances in very small proportions. Here's a more detailed breakdown: Nitrogen (N₂): Approximately 78% of the air. Oxygen (O₂): Approximately 21% of the air. Argon (Ar): Around 0.9% of the air. Carbon Dioxide (CO₂): A very small fraction, around 0.04% of the air. Other Gases: A variety of other gases, such as neon, methane, and helium, are present in trace amounts. Water Vapor: The amount of water vapor in the air can vary, but it's a significant component, particularly near the Earth's surface. Particles: The air also contains tiny particles, like dust, pollen, and pollutants, which can vary depending on location and conditions.

Question 63

Write a method for the can crushing experiment regarding air pressure.

Answer 63

1) Take an empty can and use a syringe to pour 20 cm cubed of water into the can. 2) Place the can on a gauze mat (tripod) and heat the water up over a Bunsen flame until steam is coming out of the opening. 3) carefully (quickly) use the tongs to turn the can upside down into the water in the basin (so that the hole in the top of the can is submerged in water). RESULT: THE CAN COLLAPSES INWARDS DUE TO A STRONGER EXTERNAL AIR PRESSURE.

Question 64

Glowing and lit splint test for air, oxygen, carbon dioxide and hydrogen

Answer 64

LIT air: continues to burn, but if fully put in the tube, it is extinguished oxygen: burns brighter in pure oxygen carbon dioxide: immediately put out hydrogen: squeaky pop (louder) GLOWING air: continues to glow, then extinguishes oxygen: re-lights a glowing splint carbon dioxide: immediately put out hydrogen: squeaky pop

Question 65

Changes which occur to show a chemical reaction has taken place.

Answer 65

. Change in state . Change in colour . Sparks . Bubbles . Release of energy . Change of mass