Atoms and Elements Flashcards
What is an atom ?
The smallest part of an element that can exist.
What is an element ?
A substance made up of one type of atom only, having the same number of protons in each nucleus.
What is a compound ?
A compound is a substance that contains two or more elements (in fixed portions) , chemically combined.
What is a molecule ?
A collection of two or more atoms held together by chemical bonds called covalent bonds.
What is an ion ?
Electrically charged particle, formed when an atom or molecule gains or loses electrons.
What charge does an electron have ?
A negative charge.
When are ionic compounds formed ?
When non - metals react with metals.
What are two non - metal ions that have a positive charge ?
H+ (hydrogen) and NH4+ (ammonium )
What is a covalent bond?
A bond between non-metals. When they share electrons to gain a full outer shell.
What is a metallic bond?
A bond between metals.
What is an ionic bond?
A bond between a metal and non-metal.
What are the metals in the reactivity series?
Potassium, Sodium, Lithium, Calcium, Magnesium, aluminium, CARBON, Zinc, Iron, HYDROGEN, Copper, Silver, Gold.
What is the atomic number?
The number of protons - equal to the number of electrons.
Explain why electrons and protons are equal.
Protons have a positive charge, whereas electrons have a negative charge so they must cancel each other out.
What are isotopes?
Isotopes are atoms from the same element with the same number of protons but a different number of
neutrons.
How do you know if something makes a positive ion?
- Lose electrons.
- Metals form positive ions.
- They have more protons than electrons.
How do you know if something makes a negative ion?
- Gains electrons.
- Non-metals form negative ions.
- They have more electrons than protons.
What non-metals exist as molecules?
I Bring Clay For Our New House.
Iodine, Bromine, Chlorine, Fluorine, Oxygen, Nitrogen, Hydrogen
What happens to oppositely charged ions?
They are attracted to each other by electrostatic forces to form an ionic compound.
What is the structure of the ionic bonds called?
Giant ionic lattices.
What are the properties of ionic compounds?
- High melting/ boiling points. Electrostatic forces require a lot of heat to break.
- Cannot conduct electricity, particles cannot move.
- They can conduct electricity when melted/ dissolved in water because the ions can move around.
What ions have higher forces between them?
Ions with a higher charge.
What does the period number tell you?
The period number tells you the number of electron shells/ energy levels.
What does the group number tell you?
The group number tells you the number of electrons on the outermost shell.
What does the atomic number tell you?
The atomic number tells you the total amount of electrons.
What is the chemical formula for hydrochloric acid?
The chemical formula for hydrochloric acid is HCl.
What is the chemical formula for sulphuric acid?
The chemical formula for sulphuric acid is H2SO4.
What is the chemical formula for nitric acid?
The chemical formula for nitric acid is HNO3.
What are the products of acid and metal reacting?
Acid + metal —-> salt +hydrogen
What is a base?
A base is a substance that reacts with an acid to neutralize it and produce salt.
Give two chemical properties of metals?
- They lose electrons to form positive ions.
- Metal-oxides are basic - they react with an acid to produce salt+ water.
Give two chemical properties of non-metals?
- They gain electrons to form negative ions.
- Non - metal oxides are acidic - they react with a base to produce salt +water.
What are the boiling and melting points of metals?
Metals have high melting and boiling points.
What are the melting and boiling points of non-metals?
Non - metals have low melting and boiling points.
What does the density mean?
Density means the mass of particles in a certain volume.
What does sonorous mean?
A substance that makes a sound when hit.
What does ductile mean?
Materials that can easily be bent/ drawn into wires.
What is a displacement reaction?
A displacement reaction is when a more reactive metal displaces a less reactive metal from its compounds.
What do we call the insoluble solid left behind in filtration?
Residue
What is filtration?
A separation technique that separates an insoluble solid from a liquid eg. sand and water.
What is a solute?
What is dissolving in a mixture.
What is a solvent?
What the solute is dissolving in.
What is a solution?
The solute+ solvent mixture.
What is evaporation/crystallization?
Evaporation is a separating technique that produces crystals by dissolving a solvent.
What is simple distillation?
Separating technique used to separate a solvent from a solution. Useful for producing pure water from sea water.
What is the boiling point of water?
100 degrees celcius.
What is fractional distillation?
Separating technique used to separate different liquids from a mixture of liquids. eg. crude oil.
Give an example of crystallization?
Producing copper sulphate crystals from copper sulphate solution.
In Fractional distillation, what substance is collected at the bottom of the column?
The one with the highest boiling point.
What are hydrocarbons?
A compound made of hydrogen and carbon only.
What is pure ice’s melting point?
0 degrees celcius.
When does a pure substance boil/melt?
It boils/melts at a specific temperature.
What are two ways of collecting liquids from a column in fractional distillation?
- Collect different liquids from different parts of the column. The highest boiling point is at the bottom and the lowest boiling point is at the top.
- Continue to heat mixture - a substance with the lowest boiling point is collected first.
What are positively charged ions called?
Cations.
What are negatively charged ions called?
Anions.
How do you know if the predicted state is solid?
Given temperature< melting point.
How do you know if the predicted state is liquid?
Given temperature between melting and boiling points.
What are the group 0 elements known as?
Noble gases.
What is the boiling point of noble gases?
- Low boiling points.
- Boiling point increases as you go down the group as intermolecular forces become stronger/ the atoms are larger.
Explain why noble gases are inert.
Noble gases have a full outer shell of electrons, meaning it has no tendency to lose or gain electrons. They also don’t share electrons to form molecules.
Give 3 physical properties of the group 1 elements.
- Soft (can be cut with a knife.)
- low melting point (decreases as you go down)
- Low density
What is the melting point of alkali metals?
- Low melting points.
- Decreases as you go down the group.
What are chemical properties?
How a substance reacts with other substances.
What are the products of an alkali metal reacting with water?
Alkali metal + water - metal hydroxide + hydrogen
What is the chemical symbol for potassium hydroxide?
KOH
What does aqueous mean?
Aqueous means something that can be dissolved in water.
What bases are alkali?
Bases that dissolve in water (aq)
How are alkali metals like typical metals?
- they are good conductors of heat and electricity.
- They are shiny when first cut.
What colour would sodium hydroxide turn with a universal indicator?
It will turn blue/ purple as it is an alkali - and all alkalis are bases.
What group 1 elements float in water?
- Lithium
- Sodium
- Potassium
Have low density
Density increases as you go down the group
Why does the reactivity of group 1 metals increase as you go down the group?
The outer electron is less attracted to the nucleus and therefore electron can be lost easily.
Greater distance between the positive nucleus and negative electron
The outer electron is shielded from the nucleus by internal energy levels.
What are three substances that react quickly with group 1 elements and what do they form?
- Chlorine (Metal chloride.)
- Oxygen (Metal oxide.)
- Water (Metal hydroxide + hydrogen)
What state are most non - metals at room temperature?
Unreactive gas.
What do halogens exist as?
Simple molecules.
What are the melting/ boiling points of group 7 elements?
- Low melting/ boiling points
- They increase as you go down the group
What is a base?
A base is a substance that can react with acids and neutralise them.
How do you know if the predicted state is a gas?
Given temperature> boiling point.
How do you know the number of covalent bonds an element forms?
8 - Group number
Eg. Carbon 8-4 = 4 covalent bonds
4 pairs
Why are covalent bonds very strong?
- The nuclei of both elements are strongly attracted to the covalent bond.
- Requires a lot of energy to break the covalent bond
