C1 - Atomic Structure and the Periodic Table Flashcards
What are the three main subatomic particles that make up an atom?
Protons, Neutrons, Electrons
What is the approximate radius of an atom?
About 0.1 nanometres (1 × 10-10 m)
Where is the nucleus located in an atom?
In the middle of the atom
What particles are contained in the nucleus?
Protons and Neutrons
What is the radius of the nucleus compared to the atom?
Around 1 × 10-14 m (about 1/10,000 of the radius of an atom)
What charge does the nucleus have and why?
Positive charge because of protons
Where is most of the mass of an atom concentrated?
In the nucleus
What are the charges and relative masses of protons, neutrons, and electrons?
Proton: +1 charge, heavy; Neutron: 0 charge, heavy; Electron: -1 charge, very small
How do electrons move in relation to the nucleus?
They move around the nucleus in electron shells
What determines the size of an atom?
The volume of the orbits of the electrons
What is true about the number of protons and electrons in a neutral atom?
They are equal
What is an ion?
An atom or group of atoms that has lost or gained electrons
What happens to the number of protons and electrons in an ion?
The number of protons does not equal the number of electrons
What does the atomic number represent?
The number of protons in an atom
What does the mass number represent?
The total number of protons and neutrons in the atom
How do you calculate the number of neutrons in an atom?
Subtract the atomic number from the mass number
Fill in the blank: Atoms are neutral because they have the same number of protons as _______.
Electrons
True or False: Electrons have a significant mass compared to protons and neutrons.
False
What is an element?
A substance made up of atoms that all have the same number of protons in their nucleus.
What determines the type of atom?
The number of protons in the nucleus.
How many different elements are there?
About 100 different elements.
What is the relationship between the number of protons and elements?
All atoms of a particular element have the same number of protons, while different elements have different numbers of protons.
How are atoms of each element represented?
By a one or two letter symbol.
What is an example of a straightforward atomic symbol?
C = carbon, O = oxygen, Mg = magnesium.
What is an example of a less intuitive atomic symbol?
Na = sodium, Fe = iron, Pb = lead.
Where do many atomic symbols come from?
The Latin names of the elements.
What are isotopes?
Different forms of the same element that have the same number of protons but a different number of neutrons.
What do isotopes have in common?
The same atomic number.
What is the difference between isotopes?
They have different mass numbers due to varying numbers of neutrons.
Provide an example of isotopes.
Carbon-12 and carbon-13.
How do you calculate the number of neutrons in an isotope?
Mass number minus atomic number.
What is relative atomic mass?
An average mass taking into account the different masses and abundances of all isotopes of an element.
What formula is used to calculate relative atomic mass?
sum of (isotope abundance x isotope mass number) / sum of abundances of all isotopes.
Calculate the relative atomic mass of copper with isotopes Cu-63 and Cu-65 given their abundances.
63.6
Fill in the blank: An atom with one proton is ______.
hydrogen
True or False: Isotopes of an element have the same mass number.
False
What are compounds?
Substances formed from two or more elements, with atoms in fixed proportions held together by chemical bonds.
What happens when elements react?
Atoms combine with other atoms to form compounds.
What is involved in making bonds between atoms?
Atoms giving away, taking, or sharing electrons.
Are the nuclei of atoms affected when a bond is made?
No, only the electrons are involved.
What is usually required to separate the original elements of a compound?
A chemical reaction.
What is formed when a metal and a non-metal combine?
Ions.
What type of bonding occurs between positive and negative ions?
Ionic bonding.
Give an example of a compound that is bonded ionically.
Sodium chloride, magnesium oxide, calcium oxide.
What is a compound formed from non-metals composed of?
Molecules.
What is the process called when atoms share electrons?
Covalent bonding.
Give an example of a compound that is bonded covalently.
Hydrogen chloride gas, carbon monoxide, water.
How do the properties of a compound compare to the original elements?
They are usually totally different.
What does a formula represent in chemistry?
What atoms are in a compound.
What is the formula for carbon dioxide?
CO2.
What does the formula for sulfuric acid include?
H2SO4.
What does a little number outside a bracket in a formula indicate?
It applies to everything inside the brackets.
What is the formula for water?
H2O.
What is the formula for sodium chloride?
NaCl.
What is the formula for ammonia?
NH3.
What is the formula for hydrochloric acid?
HCl.
What is the formula for calcium chloride?
CaCl2.
What is the formula for sodium carbonate?
Na2CO3.
What is the formula for sulfuric acid?
H2SO4.
What are chemical equations fundamental to?
Chemistry
What are the molecules on the left-hand side of a chemical equation called?
Reactants
What are the molecules on the right-hand side of a chemical equation called?
Products
How can chemical changes be shown in shorthand?
Using symbol equations
In a symbol equation, what do the symbols or formulas represent?
Reactants and products
What must always be true about the number of atoms in a balanced chemical equation?
The same number of atoms on both sides
What is the purpose of putting numbers in front of formulas in a chemical equation?
To balance the equation
Fill in the blank: Chemical equations must be ________ to ensure the law of conservation of mass.
Balanced
What is the first step in balancing a chemical equation?
Find an element that doesn’t balance
True or False: You can change the chemical formulas when balancing an equation.
False
What should you do if adding a number to balance one element creates another imbalance?
Pencil in another number and see where that gets you
What is the example equation given for reacting sulfuric acid with sodium hydroxide?
H₂SO₄ + NaOH → Na₂SO₄ + H₂O
In the example provided, how do you initially address the lack of H atoms on the right-hand side?
Change H₂O to 2H₂O
What adjustment is made to balance the equation after changing H₂O to 2H₂O?
Put 2NaOH on the left-hand side
How does balancing a chemical equation ensure the conservation of mass?
By ensuring atoms are neither created nor destroyed
What are mixtures in chemistry compared to?
Mixtures in chemistry are compared to mixtures in baking, with separate things mixed together.
How can mixtures be separated?
Mixtures can be separated by physical methods such as:
* Filtration
* Crystallisation
* Simple distillation
* Fractional distillation
* Chromatography
What characterizes a mixture compared to a compound?
In a mixture, there is no chemical bond between the different parts.
What types of substances can be found in a mixture?
The parts of a mixture can be either elements or compounds.
What is an example of a mixture of gases?
Air is a mixture of gases, mainly nitrogen, oxygen, carbon dioxide, and argon.
What is crude oil composed of?
Crude oil is a mixture of different length hydrocarbon molecules.
How do the properties of a mixture relate to its components?
The properties of a mixture are just a mixture of the properties of the separate parts.
True or False: The chemical properties of a substance are affected by being part of a mixture.
False
Fill in the blank: A mixture of iron powder and sulfur powder will show the properties of both _______ and _______.
iron; sulfur
What does a mixture of iron powder and sulfur powder contain?
It contains grey magnetic bits of iron and bright yellow bits of sulfur.
What are the two methods of separating soluble solids from solutions?
Evaporation and crystallisation
These methods are used to separate soluble salts from their solutions.
What does filtration separate?
Insoluble solids from liquids
Filtration is commonly used to purify substances by removing solid impurities.
What is the definition of insoluble?
The solid can’t be dissolved in the liquid
What is the first step in the evaporation process?
Pour the solution into an evaporating dish
What happens to the solvent during the evaporation process?
The solvent will evaporate and the solution will get more concentrated
True or False: Evaporation can be used if the salt decomposes when heated.
False
If the salt decomposes, crystallisation should be used instead.
What is the purpose of crystallisation?
To make nice big crystals of salt
What should you do after some solvent has evaporated in crystallisation?
Remove the dish from the heat and leave the solution to cool
What type of mixture is rock salt?
A mixture of salt and sand
How do you separate salt from sand in rock salt?
Dissolve the salt in water, filter the mixture, and evaporate the water
What is the effect of cooling a concentrated solution in crystallisation?
The salt starts to form crystals as it becomes insoluble
Fill in the blank: To separate sand from salt, you should grind the mixture to make sure the salt crystals are _______.
small
What can be used instead of a Bunsen burner for heating during evaporation?
Water bath or electric heater
What is left on the filter paper after filtration of a mixture of salt and sand?
The grains of sand
What is the final step after filtering the crystals out of a solution in crystallisation?
Leave them in a warm place to dry
What did John Dalton describe atoms as at the start of the 19th century?
Solid spheres that are positively charged
Dalton’s model suggested that different spheres made up different elements.
What conclusion did J.J. Thomson reach about atoms in 1897?
Atoms contain smaller, negatively charged particles called electrons
This led to the development of the ‘plum pudding model’.
What is the ‘plum pudding model’?
An atom is a ball of positive charge with electrons stuck in it
This model was proposed by J.J. Thomson.
What experiment did Ernest Rutherford conduct in 1909?
Alpha particle scattering experiments
Rutherford and his student fired alpha particles at a thin sheet of gold.
What did Rutherford’s alpha particle scattering experiments reveal?
The plum pudding model could not be correct
Some alpha particles were deflected more than expected, indicating a concentrated positive charge.
What is the nuclear model of the atom proposed by Rutherford?
A tiny, positively charged nucleus at the center with a cloud of negative electrons surrounding it
Most of the atom is empty space.
How did Niels Bohr’s nuclear model differ from Rutherford’s?
Electrons orbit the nucleus in fixed shells
Bohr suggested that electrons are not found anywhere in between the shells.
What did Bohr’s theory of atomic structure help to explain?
Many observations made by other scientists at the time
Bohr’s model was supported by numerous experiments.
What particles were discovered in the nucleus by further experiments?
Protons and neutrons
Protons have a positive charge, while neutrons are neutral.
Who provided evidence for the existence of neutrons?
James Chadwick
His experiments were conducted about 20 years after the acceptance of atomic nuclei.
What is the modern accepted version of the atomic model called?
The nuclear model
This model is based on the findings of Rutherford, Bohr, and Chadwick.
True or False: The plum pudding model was the final accepted theory of atomic structure.
False
The model was eventually disproven by Rutherford’s experiments.
Fill in the blank: The nucleus is where most of the __________ of the atom is concentrated.
mass
The nucleus contains protons and neutrons.
What causes the whole of chemistry?
Electrons occupy ‘shells’ around the nucleus
This concept is fundamental to understanding atomic structure and chemical reactions.
What are the Electron Shell Rules?
1) Electrons always occupy shells
2) The lowest energy levels are filled first
3) Maximum electrons per shell:
* 1st shell: 2
* 2nd shell: 8
* 3rd shell: 8
4) Atoms prefer full electron shells
5) Atoms with incomplete outer shells tend to react
These rules are crucial for predicting how atoms will interact in chemical reactions.
How many electrons can the 1st shell hold?
2 electrons
This is the maximum capacity for the first electron shell.
How many electrons can the 2nd shell hold?
8 electrons
This shell can accommodate up to 8 electrons.
How many electrons can the 3rd shell hold?
8 electrons
The 3rd shell also holds a maximum of 8 electrons.
Which group of elements has full electron shells?
Noble gases in Group O
Noble gases are stable due to their full outer electron shells.
What makes most atoms want to react?
An incomplete outer shell
Atoms tend to achieve stability by filling their outermost electron shell.
What is the electronic structure of nitrogen?
2, 5
Nitrogen has 7 electrons: 2 in the first shell and 5 in the second shell.
What is the electronic structure of magnesium?
2, 8, 2
Magnesium has 12 electrons: 2 in the first shell, 8 in the second shell, and 2 in the third shell.
Fill in the blank: The electronic configuration for sodium is _______.
2, 8, 1
This configuration indicates sodium has 11 electrons.
What is the maximum number of protons in the first 20 elements of the periodic table?
20 protons
The first 20 elements include hydrogen (1 proton) to calcium (20 protons).
What is the electronic structure of hydrogen?
1
Hydrogen has 1 electron.
What is the electronic structure of helium?
2
Helium has a full first shell with 2 electrons.
What is the electronic structure of lithium?
2, 1
Lithium has 3 electrons: 2 in the first shell and 1 in the second shell.
What is the electronic structure of carbon?
2, 4
Carbon has 6 electrons: 2 in the first shell and 4 in the second shell.
What is the electronic structure of neon?
2, 8
Neon has a full outer shell with 10 electrons.
What is the electronic structure of calcium?
2, 8, 8, 2
Calcium has 20 electrons: 2 in the first shell, 8 in the second shell, and 10 in the third shell.
What were the two obvious ways to categorize elements in the early 1800s?
1) Their physical and chemical properties
2) Their atomic weight
Scientists had no knowledge of atomic structure, protons, neutrons, or electrons at the time.
What is atomic weight equivalent to, as referred to in the text?
Relative atomic mass
Atomic weight was a primary method for categorizing elements before the understanding of atomic structure.
Why were early periodic tables incomplete?
Some elements were placed in the wrong group and were arranged by atomic weight without considering their properties.
This led to inaccuracies in the classification of elements.
Who developed a more accurate periodic table in 1869?
Dmitri Mendeleev
Mendeleev arranged 50 known elements and left gaps for undiscovered elements.
What did Mendeleev do differently in his arrangement of elements?
Put elements mainly in order of atomic weight but switched the order based on properties.
An example includes iodine being placed after tellurium despite its smaller atomic weight.
What purpose did the gaps in Mendeleev’s table serve?
To ensure elements with similar properties stayed in the same groups and to indicate undiscovered elements.
These gaps allowed for predictions about the properties of elements yet to be discovered.
What element did Mendeleev predict, which was later confirmed to exist?
Ekasilicon, known today as germanium.
Mendeleev made accurate predictions about its chemical and physical properties.
What discovery in the early 20th century supported Mendeleev’s periodic table?
The discovery of isotopes.
Isotopes have different masses but the same chemical properties, confirming the importance of properties in classification.
True or False: Mendeleev placed elements strictly in order of atomic weight.
False
He adjusted the order based on the properties of the elements.
Fill in the blank: Mendeleev’s periodic table was based on _______ and left gaps for undiscovered elements.
Atomic weight
This approach allowed for better organization and predictions in the periodic table.
What is the purpose of the periodic table?
To see patterns in properties of elements
The periodic table organizes elements in a way that reveals trends and similarities among them.
How are elements arranged in the periodic table?
In order of increasing atomic (proton) number
This arrangement reflects the periodic nature of element properties.
Where are metals located in the periodic table?
To the left
Non-metals are found to the right.
What is the group number indicative of?
The number of electrons in the outer shell
For example, Group 1 has one electron, while Group 7 has seven electrons.
What are the vertical columns in the periodic table called?
Groups
Elements in the same group share similar properties.
What can be predicted about elements in the same group?
Their properties and reactivity
Knowing one element’s properties allows predictions about others in the same group.
What are the rows in the periodic table referred to as?
Periods
Each period represents another full shell of electrons.
Fill in the blank: Elements with similar properties form _______.
Columns
True or False: Group 0 elements have one electron in their outer shell.
False
Group 0 elements, like Helium, have two electrons in their outer shell.
What trend is observed in the reactivity of Group 1 elements?
Reactivity increases as you go down the group
This means that elements like Lithium react less vigorously than Cesium.
What are the three main categories of elements in the periodic table?
Metals, Non-metals, Noble gases
Each category has distinct properties and behaviors.
What does the term ‘alkali metals’ refer to?
Group 1 elements
These elements are highly reactive and include Lithium, Sodium, and Potassium.
What is the significance of the relative atomic mass?
It helps to compare the mass of one atom to another
Relative atomic mass is a weighted average of the isotopes of an element.
Fill in the blank: The elements in Group 7 are known as _______.
Halogens
What is the unique characteristic of noble gases?
They are inert and do not readily react with other elements
Noble gases include Helium, Neon, and Argon.
Where are most metals located on the periodic table?
Towards the bottom and to the left of the periodic table
What is a key characteristic of metals in terms of ion formation?
They can form positive ions when they react
Where are non-metals found on the periodic table?
At the far right and top of the periodic table
Do non-metals generally form positive ions when they react?
No
What is the purpose of atoms reacting in terms of electron configuration?
To form a full outer shell
What is the effect of the distance of outer electrons from the nucleus in metals?
They feel a weaker attraction
Why is it easier for metals to form positive ions?
Not much energy is needed to remove the electrons
Why is it more difficult for non-metals to form positive ions?
They have lots of electrons to remove or strong attraction to the nucleus
What type of bonding do all metals exhibit?
Metallic bonding
List three basic physical properties of metals.
- Strong
- Malleable
- Good conductors of heat and electricity
What are the physical properties of non-metals compared to metals?
They tend to be dull looking, more brittle, and don’t generally conduct electricity
Fill in the blank: Non-metals often have a _______ density.
Lower
What happens to the structures of non-metals?
They form a variety of different structures
True or False: Non-metals are always solids at room temperature.
False
What type of properties do non-metals exhibit?
A wide range of chemical properties
What are Group 1 elements commonly known as?
Alkali metals
List the alkali metals in Group 1.
- Lithium
- Sodium
- Potassium
- Rubidium
- Caesium
- Francium
What is the common characteristic of alkali metals regarding their outer shell?
They all have one electron in their outer shell
How does the reactivity of alkali metals change as you go down Group 1?
Increasing reactivity
Fill in the blank: Alkali metals are ______ and have low density.
soft
What happens to the melting and boiling points of alkali metals as you go down Group 1?
Lower melting and boiling points
What type of ions do Group 1 elements readily form?
I+ ions
True or False: Alkali metals only react to form covalent compounds.
False
When alkali metals react with water, what gas is produced?
Hydrogen gas
What happens to the vigor of the reaction when moving down the alkali metals group in water?
The reaction becomes more violent
What do alkali metals produce when they react with water?
Hydroxides that dissolve in water
Complete the reaction: 2Na + 2H2O → ______ + H2.
2NaOH (aq)
What type of salts do Group 1 metals form when they react with chlorine?
White salts called metal chlorides
How does the reactivity of alkali metals with chlorine change down the group?
Reactivity increases
Fill in the blank: Group 1 metals react with oxygen to form ______.
metal oxides
What happens to alkali metals when they react with oxygen in the air?
They tarnish and form a dull metal oxide layer
What does lithium react to form when it reacts with oxygen?
Lithium oxide (Li2O)
What type of oxides does sodium form when it reacts with oxygen?
A mixture of sodium oxide (Na2O) and sodium peroxide (Na2O2)
What does potassium form when it reacts with oxygen?
A mixture of potassium peroxide (K2O2) and potassium superoxide (KO2)
What are the halogens?
All non-metals with coloured vapours.
What is the state and color of Fluorine?
A very reactive, poisonous yellow gas.
What is the state and color of Chlorine?
A fairly reactive, poisonous dense green gas.
What is the state and color of Bromine?
A dense, poisonous, red-brown volatile liquid.
What is the state and color of Iodine?
A dark grey crystalline solid or a purple vapour.
How do halogens exist in terms of molecular structure?
As molecules which are pairs of atoms.
As you go down Group 7, halogens become _______.
LESS REACTIVE.
As you go down Group 7, halogens have _______ melting and boiling points.
HIGHER.
As you go down Group 7, halogens have _______ relative atomic masses.
HIGHER.
What can be predicted about iodine compared to chlorine?
Iodine will have a higher boiling point than chlorine.
What do all Group 7 elements have in common regarding their outer shell?
They all have seven electrons in their outer shell.
Halogen atoms can share electrons via _______ bonding.
covalent.
What type of compounds do halogens form when reacting with non-metals?
Molecular compounds with simple molecular structures.
Halogens form _______ ions when they bond with metals.
I- (halides).
Examples of halide ions include _______.
- F- * Cl- * Br- * I-
The compounds formed by halogens and metals have _______ structures.
ionic.
What occurs in a displacement reaction involving halogens?
A more reactive halogen displaces a less reactive one.
Can chlorine displace bromine and iodine from their salts?
Yes.
True or False: Bromine can displace iodine from an aqueous solution.
True.
What are the Group O elements commonly known as?
Noble gases
Noble gases are known for their lack of reactivity and are often considered ‘dull’ due to their inert nature.
Which elements are included in Group O?
Helium, neon, argon, krypton, xenon, radon
These elements are characterized by having a full outer electron shell.
What is the electron configuration of helium?
2 electrons in the first shell
Helium is unique among noble gases as it only has two electrons and does not have a second energy level.
What is the state of Group O elements at room temperature?
Colourless gases
All noble gases are colorless and exist as monatomic gases at room temperature.
Why are noble gases considered inert?
They have a full outer-shell of electrons
This stability means they do not readily react with other elements.
What happens to the boiling points of noble gases as you move down the group?
They increase
The increase in boiling points is related to the increasing number of electrons and greater intermolecular forces.
What is the boiling point trend related to the relative atomic mass of noble gases?
Boiling points increase with increasing relative atomic mass
This trend is due to the greater number of electrons leading to stronger intermolecular forces.
Fill in the blank: Helium has a ______ boiling point than neon.
lower
Helium is positioned higher in the group than neon, resulting in a lower boiling point.
Predict the boiling point of xenon if radon is -62 °C and krypton is -153 °C.
-108 °C
The boiling point of xenon is estimated to be halfway between the boiling points of radon and krypton.
True or False: Noble gases are flammable.
False
Noble gases are non-flammable due to their inert nature.
What type of gas do noble gases exist as?
Monatomic gases
This means they exist as single atoms, not bonded to each other.
