All Round Chemistry

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Created on: 22nd April 2020
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Group Discussions (42)

ifiokabasi
3 months ago
organic chemistry, industrial chemistry and representative metal
Adetunji
3 months ago
Periodic table
Maranatha
3 months ago
Hello??
Oyindamola
3 months ago
Hello everyone
  • Oyindamola: I am the group admin and I apologize recent withdrawal from the group.
    Like 0    Dislike 0   3 months ago
  • Oyindamola: I believe everyone has some contributions, questions or challenges on Chemistry.
    I assure you all that we will all work together as a team in this context.
    Like 0    Dislike 0   3 months ago
  • Oyindamola: So, for easier access to learning activities, would you better prefer a WhatsApp or Telegram platform for this study?
    please, share your response ASAP so we start learning and dont forget to invite your friends too.
    Like 0    Dislike 0   3 months ago
  • Cordeltam: Telegram
    Like 0    Dislike 0   2 months ago
Cordeltam
2 months ago
Organic chemistry
  • Adetunji: Organic chemistry is study of compounds of carbon.
    Like 0    Dislike 0   2 months ago
  • Adetunji: Organic chemistry is a branch of chemistry
    that studies the structure, properties and
    reactions of organic compounds, which
    contain carbon in covalent bonding.
    Study of structure determines their chemical
    composition and formula. Study of
    properties includes physical and chemical
    properties, and evaluation of chemical
    reactivity to understand their behavior. The
    study of organic reactions includes the
    chemical synthesis of natural products,
    drugs, and polymers, and study of individual
    organic molecules in the laboratory and via
    theoretical ( in silico) study.
    The range of chemicals studied in organic
    chemistry includes hydrocarbons
    (compounds containing only carbon and
    hydrogen) as well as compounds based on
    carbon, but also containing other elements,
    especially oxygen, nitrogen, sulfur,
    phosphorus (included in many
    biochemicals) and the halogens.
    Organometallic chemistry is the study of
    compounds containing carbon–metal
    bonds.
    In addition, contemporary research focuses
    on organic chemistry involving other
    organometallics including the lanthanides,
    but especially the transition metals zinc,
    copper, palladium, nickel, cobalt, titanium.
    Like 0    Dislike 0   2 months ago
  • Cordeltam: Thank you.
    Please kindly emphasis on its calculations.
    Like 0    Dislike 0   2 months ago
  • Adetunji: Calculation in organic chemistry involve two stage.
    1.)Emperical Formula
    2.)Molecula Formula
    Like 0    Dislike 0   2 months ago
  • Adetunji: The empirical formula of a compound is the formula which expresses only the relative number of atoms of each element in the compound. Empirical formulas are sometimes called ‘the simplest formulas’ , but because they are obtained from experimental data, they are usually called empirical formulas, and are useful to: 1. Determine the molecular mass (or weight) of compounds whose molecular masses have not been known. 2. Determine the molecular masses of compounds whose molecular masses are variable, even though they have a definite percentage composition (i.e., for different compounds formed from the same elements). To Determine Empirical Formula To determine the empirical formula of a compound, we need to know: 1. The chemical composition of the compound - this is derived from experimental procedure, and can be expressed as percentage.
    2. The relative atomic masses of the
    constituent elements.
    Procedure: 1. From the chemical
    composition of the compound, and the
    relative atomic masses of the constituent
    elements given, convert the composition of
    each constituent element to number of
    moles.
    2. Derive the mole ratio of the constituent
    elements.
    3. Finally, express the mole ratio as the
    subscripts of the symbols of their respective
    element. The simplest formula obtained is
    the empirical formula.
    Example: Analysis of carbon monoxide
    shows that it is 42.9% carbon and 57.1%
    oxygen. What is its empirical formula? (C=12,
    O=16) Solution: 1. Convert the percentage
    composition of each element to number of
    moles (consider each percentage as the
    mass).
    Number of moles = mass (or %
    composition)/relative atomic mass
    For carbon, 42.9/12 = 3.58
    For oxygen, 57.1/16 = 3.58
    2. Take the ratio of their moles:
    C : O
    3.58 3.58 = 1 : 1 3.
    Express the above ratio as subscripts of the
    symbols of their respective element, we have
    C 1O1 which is better expressed as CO - this
    is the empirical formula.
    Like 0    Dislike 0   2 months ago
  • Adetunji: The Molecular Formula describe the total number of atoms or elements present in the compound.
    To Determine Molecular Formula
    The molecular formula of a compound is the
    formula expressing one mole of the
    compound. It can be derived from its
    empirical formula if the molecular mass (or
    weight) is known. The product of the mass
    of a compound from its empirical formula
    and a factor equals the molecular mass of
    the compound. From this equation, its
    molecular formula can be deduced.
    Example: Determine the molecular formula
    of a compound of molecular weight 30 amu
    whose empirical formula is CH 3 (C=12, H=1)
    Solution: mass of the compound from its
    empirical formula = CH 3 = 12+3(1) = 15
    Product of mass of compound from
    empirical formula and a factor (x) equals the
    molecular weight.
    xCH3 = 30
    15x = 30
    x = 30/15 = 2
    Thus, 2CH3
    Therefore, molecular formula = C2H6
    Note: - Many compounds have empirical
    formulas that are the same as their
    molecular formulas, for example, CO 2 is both
    the empirical and molecular formula for
    carbon(IV)oxide. Others have their empirical
    formulas different from their molecular
    formulas, example, when you see a formula
    like H 2O2, C2H6 and C6H12O6, you are
    looking at a molecular formula, the empirical
    formula is HO, CH 3 and CH2O respectively. -
    Different compounds can have the same
    empirical formula.
    Like 1    Dislike 0   2 months ago
  • Cordeltam: Thank you
    Like 0    Dislike 0   2 months ago
  • Oyindamola: Thank you so much
    Like 0    Dislike 0   2 months ago
  • Adetunji: you are welcome
    Like 0    Dislike 0   2 months ago
Oyindamola
2 months ago
THE ARRANGEMENT OF ATOMS IN THE PERIODIC TABLE

The periodic table of the elements is a method of showing the chemical elements in a table. The elements are arranged in order of increasing atomic number. Most of the work that was done to arrive at the periodic table that we know, can be attributed to a man called Dmitri Mendeleev in 1869. Mendeleev was a Russian chemist who designed the table in such a way that recurring ("periodic") trends in the properties of the elements could be shown. Using the trends he observed, he even left gaps for those elements that he thought were 'missing'. He even predicted the properties that he thought the missing elements would have when they were discovered. Many of these elements were indeed discovered and Mendeleev's predictions were proved to be correct.

To show the recurring properties that he had observed, Mendeleev began new rows in his table so that elements with similar properties were in the same vertical columns, called groups. Each row was referred to as a period. One important feature to note in the periodic table is that all the non-metals are to the right of the zig-zag line drawn under the element boron. The rest of the elements are metals, with the exception of hydrogen which occurs in the first block of the table despite being a non-metal.


A simplified diagram showing part of the Periodic Table
You can view an online periodic table at Periodic table. The full periodic table is also reproduced at the front of this book.

Activity: Inventing the periodic table
You are the official chemist for the planet Zog. You have discovered all the same elements that we have here on Earth, but you don't have a periodic table. The citizens of Zog want to know how all these elements relate to each other. How would you invent the periodic table? Think about how you would organize the data that you have and what properties you would include. Do not simply copy Mendeleev's ideas, be creative and come up with some of your own. Research other forms of the periodic table and make one that makes sense to you. Present your ideas to your class.

Groups in the periodic table
A group is a vertical column in the periodic table and is considered to be the most important way of classifying the elements. If you look at a periodic table, you will see the groups numbered at the top of each column. The groups are numbered from left to right starting with 1 and ending with 18. This is the convention that we will use in this book. On some periodic tables you may see that the groups are numbered from left to right as follows: 1, 2, then an open space which contains the transition elements, followed by groups 3 to 8. Another way to label the groups is using Roman numerals. In some groups, the elements display very similar chemical properties and the groups are even given separate names to identify them.

The characteristics of each group are mostly determined by the electron configuration of the atoms of the element.

Group 1: These elements are known as the alkali metals and they are very reactive.

Electron diagrams for some of the Group 1 elements, with sodium and potasium incomplete; to be completed as an excersise.
Group 2: These elements are known as the alkali earth metals. Each element only has two valence electrons and so in chemical reactions, the group 2 elements tend to lose these electrons so that the energy shells are complete. These elements are less reactive than those in group 1 because it is more difficult to lose two electrons than it is to lose one.
Group 13 elements have three valence electrons.
Group 16: These elements are sometimes known as the chalcogens. These elements are fairly reactive and tend to gain electrons to fill their outer shell.
Group 17: These elements are known as the halogens. Each element is missing just one electron from its outer energy shell. These elements tend to gain electrons to fill this shell, rather than losing them. These elements are also very reactive.
Group 18: These elements are the noble gases. All of the energy shells of the halogens are full and so these elements are very unreactive.

Electron diagrams for two of the noble gases, helium (He) and neon (Ne).
Transition metals: The differences between groups in the transition metals are not usually dramatic.
  • Oyindamola: Hello everyone, my above post on the periodic table is open for discussions, brainstorming, contributions and please indicate any misunderstanding. Remember we are all here to learn and understand from others. If anyone has contributions, feel free to post it. I will subsequently post other topics indicated by members. Thank you.
    Like 0    Dislike 0   2 months ago
  • Oyindamola: TIPS AND MINOR RESEARCH

    The number of valence electrons of an element corresponds to its group number on the periodic table.
    INTERESTNG FACT:
    Group 15 on the periodic table is sometimes called the pnictogens.

    Use a periodic table to help you to complete the last two diagrams for sodium (Na) and potassium (K).
    What do you notice about the number of electrons in the valence energy level in each case?
    Explain why elements from group 1 are more reactive than elements from group 2 on the periodic table (Hint: Think about the 'ionisation energy').
    It is worth noting that in each of the groups described above, the atomic diameter of the elements increases as you move down the group. This is because, while the number of valence electrons is the same in each element, the number of core electrons increases as one moves down the group.
    Like 0    Dislike 0   2 months ago
  • Oyindamola: SECTION B

    Periods in the periodic table
    A period is a horizontal row in the periodic table of the elements. Some of the trends that can be observed within a period are highlighted below:

    As you move from one group to the next within a period, the number of valence electrons increases by one each time.
    Within a single period, all the valence electrons occur in the same energy shell. If the period increases, so does the energy shell in which the valence electrons occur.
    In general, the diameter of atoms decreases as one moves from left to right across a period. Consider the attractive force between the positively charged nucleus and the negatively charged electrons in an atom. As you move across a period, the number of protons in each atom increases. The number of electrons also increases, but these electrons will still be in the same energy shell. As the number of protons increases, the force of attraction between the nucleus and the electrons will increase and the atomic diameter will decrease.
    Ionisation energy increases as one moves from left to right across a period. As the valence electron shell moves closer to being full, it becomes more difficult to remove electrons. The opposite is true when you move down a group in the table because more energy shells are being added. The electrons that are closer to the nucleus 'shield' the outer electrons from the attractive force of the positive nucleus. Because these electrons are not being held to the nucleus as strongly, it is easier for them to be removed and the ionisation energy decreases.
    In general, the reactivity of the elements decreases from left to right across a period.
    The formation of halides follows the general pattern: XCln (where X is any element in a specific group and n is the number of that specific group.). For example, the formula for the halides of group 1 will be XCl, for the second group the halides have the formula XCl2 and in the third group the halides have the formula XCl3. This should be easy to see if you remember the valency of the group and of the halides.
    The formation of oxides show a trend as you move across a period. This should be easy to see if you think about valency. In the first group all the elements lose an electron to form a cation. So the formula for an oxide will be X2O. In the second group (moving from left to right across a period) the oxides have the formula XO. In the third group the oxides have the formula X2O3.

    Several other trends may be observed across a period such as density, melting points and boiling points. These trends are not as obvious to see as the above trends and often show variations to the general trend.

    Electron affinity and electronegativity also show some general trends across periods. Electron affinity can be thought of as how much an element wants electrons. Electron affinity generally increases from left to right across a period. Electronegativity is the tendency of atoms to attract electrons. The higher the electronegativity, the greater the atom attracts electrons. Electronegativity generally increases across a period (from left to right). Electronegativity and electron affinity will be covered in more detail in a later grade.

    You may see periodic tables labeled with s-block, p-block, d-block and f-block. This is simply another way to group the elements. When we group elements like this we are simply noting which orbitals are being filled in each block. This method of grouping is not very useful to the work covered at this level.

    Using the properties of the groups and the trends that we observe in certain properties (ionization energy, formation of halides and oxides, melting and boiling points, atomic diameter) we can predict the the properties of unknown elements. For example, the properties of the unfamiliar elements Francium (Fr), Barium (Ba), Astatine (At), and Xenon (Xe) can be predicted by knowing their position on the periodic table. Using the periodic table we can say: Francium (Group 1) is an alkali metal, very reactive and needs to lose 1 electron to obtain a full outer energy shell; Barium (Group 2) is an alkali earth metal and needs to lose 2 electrons to achieve stability; Astatine (Group 7) is a halogen, very reactive and needs to gain 1 electron to obtain a full outer energy shell; and Xenon (Group 8) is a noble gas and thus stable due to its full outer energy shell. This is how scientists are able to say what sort of properties the atoms in the last period have. Almost all of the elements in this period do not occur naturally on earth and are made in laboratories. These atoms do not exist for very long (they are very unstable and break apart easily) and so measuring their properties is difficult.

    Exercise: Elements in the periodic table
    Refer to the elements listed below:

    Lithium (Li)
    Chlorine (Cl)
    Magnesium (Mg)
    Neon (Ne)
    Oxygen (O)
    Calcium (Ca)
    Carbon (C)
    Which of the elements listed above:

    1.belongs to Group 1
    2.is a halogen
    3.is a noble gas
    4.is an alkali metal
    5.has an atomic number of 12
    6.has 4 neutrons in the nucleus of its atoms
    7.contains electrons in the 4th energy level
    8.has only one valence electron
    9.has all its energy orbitals full
    10.will have chemical properties that are most similar
    11.will form positive ions

    WE SHOULD ALL TRY TO PRACTICE THIS EXERCISE FOR PROPER UNDERSTANDING.
    THANK YOU!!
    Like 0    Dislike 0   2 months ago
  • Oyindamola: IONISATION ENERGY

    Ionisation energy is the energy that is needed to remove one electron from an atom. The ionisation energy will be different for different atoms.

    The second ionisation energy is the energy that is needed to remove a second electron from an atom, and so on. As an energy level becomes more full, it becomes more and more difficult to remove an electron and the ionisation energy increases. On the Periodic Table of the Elements, a group is a vertical column of the elements, and a period is a horizontal row. In the periodic table, ionisation energy increases across a period, but decreases as you move down a group. The lower the ionisation energy, the more reactive the element will be because there is a greater chance of electrons being involved in chemical reactions
    SUMMARY:
    1. Elements are arranged in periods and groups on the periodic table. The elements are arranged according to increasing atomic number.
    2.A group is a column on the periodic table containing elements with similar properties. 3. A period is a row on the periodic table.
    The groups on the periodic table are labeled from 1 to 8. The first group is known as the alkali metals, the second group is known as the alkali earth metals, the seventh group is known as the halogens and the eighth group is known as the noble gases. Each group has the same properties.
    Several trends such as ionisation energy and atomic diameter can be seen across the periods of the periodic table
    4. An ion is a charged atom. A cation is a positively charged ion and an anion is a negatively charged ion.
    When forming an ion, an atom will lose or gain the number of electrons that will make its valence energy level full.
    5. An element's ionisation energy is the energy that is needed to remove one electron from an atom.
    6. Ionisation energy increases across a period in the periodic table.
    7. Ionisation energy decreases down a group in the periodic table.

    Thank you!!
    Like 0    Dislike 0   2 months ago
  • Oyindamola: Please, try and use this diagram of the periodic table for better knowledge.
    Don't forget to share your contributions, ideas and comments.
    Like 0    Dislike 0   2 months ago
  • Oyindamola: NOTE; To enhance your contributions, try to make meaningful reaearchs from the internet and books. My post is a broad compilation of several materials that will be useful for learning. Remember that the main aim is to impact knowledge.
    Like 0    Dislike 0   2 months ago
  • Adetunji: Thank you the Admin
    Like 0    Dislike 0   2 months ago
Cordeltam
2 months ago
Hydrocarbons
  • Adetunji: Hydrocarbon, any of a class of organic chemical compounds composed only of the elements carbon (C) and hydrogen (H). The carbon atoms join together to form the framework of the compound, and the hydrogen atoms attach to them in many different configurations. Hydrocarbons are the principal constituents of petroleum and natural gas. They serve as fuels and lubricants as well as raw materials for the production of plastics, fibres, rubbers, solvents, explosives, and industrial chemicals.
    Many hydrocarbons occur in nature. In addition to making up fossil fuels, they are present in trees and plants, as, for example, in the form of pigments called carotenes that occur in carrots and green leaves. More than 98 percent of natural crude rubber is a hydrocarbon polymer, a chainlike molecule consisting of many units linked together. The structures and chemistry of individual hydrocarbons depend in large part on the types of chemical bonds that link together the atoms of their constituent molecules
    Like 0    Dislike 0   2 months ago
  • Cordeltam: Calculations please...
    Like 0    Dislike 0   2 months ago
  • Adetunji: it share the same calculation with organic chemistry.
    And there are some important subtopic in hydrocarbon
    Like 0    Dislike 0   2 months ago
  • Adetunji: Hydrocarbon are categorized into two: they are Aliphatic and Aromatic hydrogen.
    Aliphatic hydrocarbon are Alkanes, Alkenes, and Alkynes while Aromatic hydrocarbons are all compounds of benzene
    Like 0    Dislike 0   2 months ago
  • Adetunji: Alkanes are saturated hydrocarbons with general molecular formula of CnH2n+2.
    All the members are differby CH2
    Like 0    Dislike 0   2 months ago
K
2 months ago
i have a question. it requires a solved answer

Ethane burns completely in oxygen according to the equation below; C2H6(g) + 7/2 O2(g) → 2CO2(g) + 3H2O(g)
What is the amount in moles of carbon (IV) oxide will be produced when 6.0g of ethane are completely burnt in oxygen.
  • Adetunji: C2H6+7/2O==2CO2+3H2O
    MM of ethane is 30g/mole and
    MM of CO2 is 44g/mole
    Mole= 1:2
    Number of mole of ethane is reacting mass/molar mass
    16/30= 0.2moles
    the mole of CO2 is 2*0.2/1
    The mole of CO2 is 0.4 mole
    Like 0    Dislike 0   2 months ago
Oyindamola
2 weeks ago
Hello everyone 🤗
  • Oyindamola: I will be opening a WhatsApp and Telegram group chat for us. Maybe the group will be more active with that🤔.. Please, this time I promise it's going to be more interesting and rewarding.. infact, it goes beyond just Chemistry... We can also ask, learn, and discuss about other science subjects. Please, feel free to join and invite your friends also. Interested members should kindly forward their WhatsApp and/or Telegram number below. Thank you all and remain safe..
    Like 0    Dislike 0   2 weeks ago
  • Oyindamola: You are free to join any or both groups.. Feel free to share the group with your friends too
    Like 2    Dislike 0   2 weeks ago
Oyindamola
3 days ago
Hey friends🙂 Did you know? Honey is the only food that will never rot.
Let's talk about our challenges, questions, contributions and advices on dealing with Chemistry.

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