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Matter

Matter. Pure substances. Impure substances: mixtures. Elements. Compounds. Homogenous. Heterogeneous. Hydrogen Oxygen Carbon. Water Acetic Acid (Vinegar) Ethanol. Solutions: Salt water Sugar water.

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Matter

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  1. Matter Pure substances Impure substances: mixtures Elements Compounds Homogenous Heterogeneous Hydrogen Oxygen Carbon Water Acetic Acid (Vinegar) Ethanol Solutions: Salt water Sugar water Chalk and water, Oil and water. Basically, substances that are not miscible when mixed. Other examples Element: A pure substance considered not to be divisible into smaller parts. Atom: The atom is the smallest part that can be derived when an element is divided by chemical means such as electrolysis. Fe Iron Fluorine CO 2 Carbon dioxide Compound: a pure substance formed from the combination of two or more elements. DNA

  2. Elements: elements are the building block of all substances on Earth and you can say: the universe. When elements combine, they can form many, many compounds, all with different characteristics. When these elements combine, their properties change. For instance: Oxygen (O2) is a gas at room temperature, but when combined with hydrogen (H2) gas, it is no longer a gas at room temperature. Oxygen and hydrogen combine to make water (H2O).

  3. ATOMS AND ELEMENTS Carbon atoms are arranged in sheets to form graphite which is used in pencil filling. Carbon

  4. Carbon atoms are arranged in a pyramid-like shape to form diamonds under high heat and pressure. Carbon

  5. Sulphur Sulphur atoms are arranged in into crystals that from rocks. Sulphur emits a foul odour that reminds you of rotten eggs.

  6. Charcoal Potassium Iron Sulphur

  7. Compounds

  8. Sodium Chlorine Sodium Chloride Na Cl Na Cl

  9. Key POINTS The atom • The word atom comes from the Greek word atomos, which means “indivisible”. • Atoms are like letters of the alphabet, they form all existing substances. • Atoms can combine in many ways to form molecules, just as letters combine to form the words of a language. • We know that atoms combine to form molecules, there is an infinite number of different combinations that exist.

  10. Key POINTS Atomic theory • We’ve seen in the past particle theory. Now, we will discuss atomic theory which will explain the structure of matter even further: • The main principles of atomic theory are: • All matter is made of tiny particles called atoms • Atoms are made of even smaller particles called protons, neutrons and electrons. • Atoms can be distinguished from each other by their number of protons, neutrons and electrons. • A set of atoms, each of which has the same number of protons, is called an “element”. • Atoms combine to form molecules.

  11. The simplified atomic model:

  12. The atomic model: breakdown of the strucutre e- e- e- e- e- e- e- e- Electron e- Nucleus: Composed of the proton and the neutron. e- e-

  13. e- e- e- 1 IA 18 VIA 2 IIA 13 IIIA 14 IVA 15 VA 16 VIA 17 VIA Li Lithium: Group number one, hence one valence electron Period two, hence two electron shells or levels

  14. e- e- e- e- e- e- e- e- e- e- e- 1 IA 18 VIA 2 IIA 13 IIIA 14 IVA 15 VA 16 VIA 17 VIA Na Sodium: Group number one, hence one valence electron Period three, hence three electron shells or levels

  15. Li e- e- e- Na e- e- e- e- e- e- e- e- e- e- e- K e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e-

  16. e- e- e- e- e- e- e- e- e- So, according to atomic theory, we know that an element contains identical atoms. e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e-

  17. Key POINTS Atomic theory • Since an element is a group of atoms that have the same number of protons, this number can be considered a characteristic property. • Yet, atoms of a given element can sometimes differ: • In their number of neutrons • Sometimes, they are prone to giving, receiving or sharing electrons with other atoms

  18. Fact: if we fill an Olympic- sized swimming pool with hydrogen (The simplest of all elements having only one proton and one electron), it would weigh 1kg. It is also explosive, in its liquid state, it is used as a rocket fuel. (Also see Zepplin Hindenburg)

  19. Key POINTS The periodic table: ingredients of matter • Suppose your teacher asks you to find the missing numbers in this table. How would you solve this problem?

  20. Key POINTS Periodic table • In science, a similar situation occurred when the information about the elements was first compiled. • Was there a way to organize the elements so that their properties would become more apparent and easier to understand? • Well, in 1869, a Siberian chemist, Dmitri Ivanovitch Mendeleev provided the best solution to this question. • He began by placing the elements on cards. • He then placed the cards on a wall • At one point, he ordered them by atomic mass • He then placed elements with similar properties in a column, and so the periodic table was born. • Mendeleev was even able to predict elements that were missing in his periodic table, and he was proven right.

  21. Dimitri Mendeleev (Russian: Дми́трий Ива́нович Менделе́ев, Dimitriy Ivanovich Mendeleyev (8 February [O.S. 27 January] 1834 in Tobolsk – 2 February [O.S. 20 January] 1907 in Saint Petersburg), was a Russian chemist. He is credited as being the primary creator of the first version of the periodic table of elements. Unlike other contributors to the table, Mendeleev predicted the properties of elements yet to be discovered.

  22. Key POINTS Characteristics of the periodic table • The periodic table contains all natural and artificial elements known to date. • The table contains ingredients of all matter on the Earth and in the Universe. • The elements are laid out in rows and columns.

  23. Key POINTS Characteristics of the periodic table • In rows: elements are organized in ascending order of atomic number. • The atomic number corresponds to proton number. • Each row is called a period.

  24. Key POINTS Characteristics of the periodic table • In columns: each column corresponds to a family or group. • Each family contains elements that have similar properties. • For example, elements of the first column form compounds with elements of column 17 or 7A and elements of the last family is made of rare elements that are non-reactive or inert, this family is called the “noble gases”.

  25. Metals (Representative elements) Metals (Transition elements) Metals (Actinides and lanthanides) Metalloids (semi-metals) Non-metals

  26. Key POINTS Chemical symbols: a universal code • Periodic tables are used all over the world. Yet, the names of the elements vary according to language. But the symbol remains the same. • For instance: The element nitrogen has the symbol N in English. In French, nitrogen still has the symbol N, but it is called azote.

  27. Key POINTS Chemical symbols: a universal code • Each element in the periodic table has its own symbol. • Some elements have one letter (Written in upper case) as its symbol, others have two letters, one uppercase, the second in lowercase. • The names of the elements are based on Latin, ancient Greek or other languages.

  28. Key POINTS The molecules: a group of atoms • In nature, elements are rarely found alone as atoms. For instance, hydrogen which is the most common element in the Universe. It is usually found in the form of a dihydrogen molecule (Two hydrogen atoms combined) • The same occurs for carbon which is found in certain gases such as carbon monoxide (CO) and carbon dioxide (CO2).

  29. Key POINTS The molecules: a group of atoms • When two or more atoms join together, they form a molecule. These molecules then combine to form all visible objects. But also invisible objects such as air.

  30. Key POINTS Chemical formulas: a practical system • A chemical formula represents the molecules and indicates which elements the molecules contain. • The formula for water, H2O, contains the symbols of the elements and the number of atoms in the molecule.

  31. Show Aardvark periodic table. Chemsketch

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