What is a gaseous atom

Understanding chemistry 4, student book

17 Principles of Structure of Matter 3. What do the elements of a group have in common? The eighteen vertical columns in the periodic table are called groups. The two lines below (lanthanoids and actinoids) belong to the elements of the 3rd group. The elements of a group have the same number of outer electrons and therefore behave similarly in chemical reactions. Element relationships (Fig.17.1) E1 A lentil-sized piece of lithium is placed in a small closable (dry!) ​​Tea strainer. The tea strainer is immersed in a beaker filled with water (250ml + 1 drop of washing-up liquid). Lithium dissolves in water and evolves hydrogen gas that can be ignited. The same experiment works with a piece of sodium. Lithium (Li) and sodium (Na) are elements of the 1st group. They each have an outer electron and therefore behave chemically in a similar way. 4. What can you read in your periodic table? On your periodic table ( page 118) you will find further information on each element about its properties: • The color of the box shows you whether the element is solid, liquid or gaseous at room temperature (20 ° C). • Ordinal number Z: number of protons (p +) and electrons (e -). • Relative atomic mass A r: number of p + and neutrons (n ​​0). The point number results from the fact that not every atom of an element has the same number of n 0. • Oxidation number: indicates how many outer electrons an atom can release (positive oxidation number) or take up (negative oxidation number). • Melting point and boiling point in ° C • Density in g / cm 3 (for gases in g / dm 3) • Electronegativity: The lower the electronegativity, the easier external electrons are emitted. • Mass fraction in the earth's shell: How often does the element occur on earth (on land, in water, in the air, in living beings)? • Stable or radioactive? Most naturally occurring atoms have stable atomic nuclei. With elements from atomic number 84 (Po) the atomic nuclei decay - they are unstable or radioactive. • Artificial elements: some elements do not occur in nature and are manufactured in laboratories. • Necessary for life? The basic elements of life are H, C, N and O. The body needs some other elements in larger quantities. These elements are Na, Mg, P, S, Cl, K and Ca. You need very small amounts of trace elements (e.g. Si and Fe). Can you name all of the specified elements? Can you find the rest of the trace elements on your periodic table? Find special natural elements! (Solutions  page 108) Which element has the highest melting point and which has the lowest? Which element has the greatest density, which the smallest? Which element occurs most frequently / least often in the earth's envelope? How many natural gaseous elements are there? LV1 Na 17.1 Element Relationships Li elements of a group (vertical column) often have similar properties because they have the same number of outer electrons. M Sodium Na Lithium Li 11p + 3p + 17.2 elements of the same group have the same number of outer electrons. 17.3 The trace element zinc (Zn) is particularly found in shellfish and is important for many processes in the body. 17.4 The element with the highest melting point glows! Worksheets j2q6c9 For testing purposes only - property of the publisher öbv

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