What are atoms?
Atoms are the smallest part of an element that can exist.
What does the chemical symbol 'O' represent?
An atom of oxygen.
What is an element?
A substance with only one type of atom.
How many different elements are there approximately?
About 100 different elements.
How are elements classified in the periodic table?
As metals or non-metals depending on their properties.
What are the columns in the periodic table called?
Groups.
What are the rows in the periodic table called?
Periods.
What are compounds made from?
Two or more different elements combined in fixed proportions.
How can compounds be represented?
By formulae using the symbols of the atoms from which they are formed.
Do compounds have the same properties as the elements they are made from?
No, compounds have different properties.
How can compounds be separated into elements?
Only by chemical reactions.
What is a mixture?
A mixture consists of two or more elements or compounds not chemically combined.
What remains unchanged in a mixture?
The chemical properties of each substance.
What physical processes can separate mixtures?
Filtration, crystallisation, simple distillation, fractional distillation, chromatography.
What type of mixture does simple distillation separate?
A soluble solid and a liquid (e.g., salt and water).
What is the purpose of evaporation in crystallisation?
To separate a soluble solid from a non-flammable liquid.
What is the function of the evaporating basin?
It provides a large surface area for quicker evaporation.
What type of mixture does filtration separate?
An insoluble solid suspended in a liquid (e.g., sand and water).
What is the residue in filtration?
The insoluble solid caught in the filter paper.
What type of mixture does fractional distillation separate?
Soluble liquids with different boiling points (e.g., crude oil).
What does the fractionating column do?
It has a temperature gradient, hotter at the bottom than at the top.
What was the plum-pudding model of the atom?
It suggested that the atom was a ball of positive charge with electrons embedded in it.
What was the belief about atoms before the discovery of the electron?
Atoms were thought to be tiny spheres that could not be divided.
What model replaced the plum-pudding model?
The nuclear model replaced the plum-pudding model.
Where is all the mass of the atom located?
In the nucleus.
What did Neils Bohr suggest about electron orbits?
Electrons orbit the nucleus at specific distances.
What are the energy levels for electrons called?
They are called shells.
What particle was named for the positive charge in the nucleus?
The proton.
Who provided evidence for the existence of neutrons?
James Chadwick.
What happens to most alpha particles directed at gold foil?
Most pass through, but a few bounce back.
What is the relative mass and charge of a proton?
Relative mass: 1, Relative charge: +1.
What is the relative mass and charge of a neutron?
Relative mass: 1, Relative charge: 0.
What is the relative mass and charge of an electron?
Relative mass: Very small, Relative charge: -1.
What is the atomic number of an element?
The number of protons in the nucleus.
What is the mass number of an atom?
The total number of protons and neutrons.
How do you calculate the number of neutrons in an atom?
Subtract the atomic number from the mass number.
What are isotopes?
Atoms of the same element with different numbers of neutrons.
How is the relative atomic mass calculated?
R.A.M = Σ (isotopic mass x % abundance) / 100.
What is the maximum number of electrons in the first energy level?
2 electrons.
How many electrons can the second and third energy levels hold?
Up to 8 electrons each.
What do elements in the same group of the periodic table have in common?
The same number of outer electrons.
What do elements in the same group of the periodic table have in common?
They have the same number of electrons in their outer shell.
What are the elements in Group 0 called?
Noble gases.
Why are noble gases unreactive?
Their atoms have stable arrangements of electrons.
What do elements in the same period have in common?
They have the same number of energy levels.
How are elements arranged in the modern periodic table?
By atomic (proton) number and similar properties in groups.
Why is it called a 'periodic' table?
Similar properties occur at regular intervals.
What does atomic number indicate?
The number of protons or electrons in an atom.
What happens as you go down a group in the periodic table?
The number of shells increases.
What did Mendeleev do to improve the periodic table?
He left gaps for undiscovered elements and changed the order based on atomic weights.
What are metals in the periodic table?
Elements that react to form positive ions.
Where are metals located in the periodic table?
To the left and towards the bottom.
What are non-metals in the periodic table?
Elements that do not form positive ions.
What is a characteristic of Group 1 elements?
They all have 1 electron in their highest energy level.
Why are Group 1 metals stored under oil?
To prevent them from reacting with oxygen or water.
How does reactivity change in Group 1 elements?
Reactivity increases as you go down the group.
What do Group 1 metals release when they react with water?
They release hydrogen and form hydroxides.
What is the reaction of sodium with water?
2Na + 2H2O → 2NaOH + H2.
What type of compounds do Group 1 metals form with non-metals?
Ionic compounds with a +1 charge.
What is the reaction of sodium with chlorine?
2Na + Cl2 → 2NaCl.
How many electrons do noble gases have in their outer shell?
Eight electrons.
What are noble gases known for?
They are unreactive and do not easily form molecules due to stable electron arrangements.
How many electrons do noble gases have in their outer energy level?
Eight electrons, except for helium which has two.
What trend occurs in the boiling points of noble gases?
Boiling points increase with increasing relative atomic mass going down the group.
How many electrons do elements in Group 7 have in their highest energy level?
Seven electrons.
What type of vapours do halogens have?
Coloured vapours.
What is the molecular structure of halogens?
They consist of molecules made up of pairs of atoms (e.g., Cl2, Br2, I2).
What charge does the halide ion carry?
The halide ion carries a charge of -1.
What type of compounds do halogens form with non-metals?
Molecular (simple covalent) compounds.
What can a more reactive halogen do in a displacement reaction?
Displace a less reactive halogen from its salt solution.
What color appears when Br2 is formed in a displacement reaction?
An orange color.
What color appears when I2 is formed in a displacement reaction?
A brown color.
What trends occur in Group 7 as you go down the group?
Higher relative molecular mass, higher melting and boiling points, and less reactivity.
What happens to reactivity as you go down Group 7?
Reactivity decreases.
What happens to atoms as you go down Group 7?
Atoms get bigger and outer shell electrons are further from the nucleus.
Where are transition metals located in the periodic table?
Between Groups 2 and 3.
What are some properties of transition metals compared to Group 1 metals?
Higher melting points (except mercury), higher densities, stronger, harder, and less reactive.
What characteristics do many transition elements have?
Ions with different charges, form colored compounds, and are useful as catalysts.
How are elements classified in the periodic table?
As metals or non-metals depending on their properties.
How can compounds be represented?
By formulae using the symbols of the atoms from which they are formed.
Do compounds have the same properties as the elements they are made from?
No, compounds have different properties.
What physical processes can separate mixtures?
Filtration, crystallisation, simple distillation, fractional distillation, chromatography.
What type of mixture does simple distillation separate?
A soluble solid and a liquid (e.g., salt and water).
What is the purpose of evaporation in crystallisation?
To separate a soluble solid from a non-flammable liquid.
What is the function of the evaporating basin?
It provides a large surface area for quicker evaporation.
What type of mixture does filtration separate?
An insoluble solid suspended in a liquid (e.g., sand and water).
What type of mixture does fractional distillation separate?
Soluble liquids with different boiling points (e.g., crude oil).
What does the fractionating column do?
It has a temperature gradient, hotter at the bottom than at the top.
What was the plum-pudding model of the atom?
It suggested that the atom was a ball of positive charge with electrons embedded in it.
What was the belief about atoms before the discovery of the electron?
Atoms were thought to be tiny spheres that could not be divided.
What did Neils Bohr suggest about electron orbits?
Electrons orbit the nucleus at specific distances.
What happens to most alpha particles directed at gold foil?
Most pass through, but a few bounce back.
What is the relative mass and charge of an electron?
Relative mass: Very small, Relative charge: -1.
How do you calculate the number of neutrons in an atom?
Subtract the atomic number from the mass number.
What do elements in the same group of the periodic table have in common?
The same number of outer electrons.
What do elements in the same group of the periodic table have in common?
They have the same number of electrons in their outer shell.
How are elements arranged in the modern periodic table?
By atomic (proton) number and similar properties in groups.
What did Mendeleev do to improve the periodic table?
He left gaps for undiscovered elements and changed the order based on atomic weights.
What is a characteristic of Group 1 elements?
They all have 1 electron in their highest energy level.
What do Group 1 metals release when they react with water?
They release hydrogen and form hydroxides.
What are noble gases known for?
They are unreactive and do not easily form molecules due to stable electron arrangements.
How many electrons do noble gases have in their outer energy level?
Eight electrons, except for helium which has two.
What trend occurs in the boiling points of noble gases?
Boiling points increase with increasing relative atomic mass going down the group.
What is the molecular structure of halogens?
They consist of molecules made up of pairs of atoms (e.g., Cl2, Br2, I2).
What can a more reactive halogen do in a displacement reaction?
Displace a less reactive halogen from its salt solution.
What trends occur in Group 7 as you go down the group?
Higher relative molecular mass, higher melting and boiling points, and less reactivity.
What happens to atoms as you go down Group 7?
Atoms get bigger and outer shell electrons are further from the nucleus.
What are some properties of transition metals compared to Group 1 metals?
Higher melting points (except mercury), higher densities, stronger, harder, and less reactive.
What characteristics do many transition elements have?
Ions with different charges, form colored compounds, and are useful as catalysts.
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