ELEMENTS AND PERIODICITY (GROUP 1,2,3,4 & HALOGEN).pptx

ELEMENT & PERIODICITY
GROUP 1, 2, 3, 4 AND HALOGEN

1. Elements and periodicity Group 1,2,3,4 and halogen

2. The  periodic law  (also referred to as M endeleev’s law), states that the chemical properties of elements are a periodic function of their atomic weights. Moseley gave the  modern periodic law  which states that physical and chemical properties of the elements are the periodic function of their atomic numbers The modern periodic table consists of 18 vertical columns, called the groups(1-18) and 7 Horizontal rows, called periods. The first period contains two elements, Hydrogen and Helium. The second period contains eight elements, from Lithium to Neon. The third period contains eight elements, from Sodium to Argon. The fourth period contains eighteen elements, from Potassium to Krypton. ”.

3. The fifth period contains  eighteen elements,  from rubidium to xenon. The sixth period contains  thirty-two elements. The seventh period is incomplete . On the basis of electronic configuration, elements are classified into  four blocks  known as  s, p, d and f- blocks . 1st and 2nd group elements are called  s-block  elements. The general electronic configuration is  ns 1-2 . 13th to 18th group elements are called  p-block  elements. The general electronic configuration is  ns 2  np 1-6 . 3rd to 12th group elements are called  d-block  elements. The general electronic configuration is ( n-1)d 1-10  ns 1-2 . Lanthanides and actinides elements are called  f-block  elements. The general electronic configuration is  (n-2)f 1-14  (n-1)d 0-1  ns 2 .

4. Group 1 & 2 elements Metals lose electron(s) to form positive ion(s) Group 1 & 2 elements are called alkali metals and alkaline earth metals respectively Group 1 metals are chemical elements having an unpaired electron in the outermost s orbital. These metals are named as alkali metals because they form chemical compounds which are alkaline when dissolved in water. We can observe these elements in the first column of the s block of the periodic table. The members of this group 1 metals are as follows: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rh), Caesium (Cs), Francium ( F r). Group 1 metals are all shiny, highly reactive, and very soft (we can easily cut them using a simple knife). Generally, the metals in this group show low densities, low melting points, low boiling points and have body- centred cubic crystal structures. Furthermore, they have distinct flame colours , so we can easily distinguish them by exposing a sample to a bunsen burner. Group 1 elements have 1 electron in the outer shell and group 2 have 2 R eactivity in both cases increases down the group because as the atomic radius increases ionization energy decreases hence metals down the group lose that one electron easier than those at the top of the group

5. Electronic configuration of group 2 elements Element Symbol  Atomic Number Electronic Configuration Lithium Li 3 1s 2 2s 1 1𝑠22𝑠1 Sodium Na 11 1s 2 2s 2 2p 6 3s 1 1𝑠22𝑠22𝑝63𝑠1 Potassium K 19 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 1 1𝑠22𝑠22𝑝63𝑠23𝑝63𝑑104𝑠1 Rubidium  Rb 37 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 1 1𝑠22𝑠22𝑝63𝑠23𝑝63𝑑104𝑠24𝑝64𝑑105𝑠1 Caesium   Cs 55 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 1 1𝑠22𝑠22𝑝63𝑠23𝑝63𝑑104𝑠24𝑝64𝑑104𝑓145𝑠25𝑝65𝑑106𝑠1 Francium Fr 87 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 2 6p 6 7s 1 1𝑠22𝑠22𝑝63𝑠23𝑝63𝑑104𝑠24𝑝64𝑑104𝑓145𝑠25𝑝65𝑑106𝑠26𝑝67𝑠1

6. Electronic configuration of group 1 elements Element Symbol  Atomic Number Electronic Configuration Beryllium Be 4 2:2 Magnesium Mg 12 2 : 8 : 2 Calcium Ca 20 2 : 8 : 8 : 2 Strontium Sr 38 2 : 8 : 18 : 8 : 2 Barium Ba 56 2 : 8 : 18 : 18 : 8 : 2 Radium Ra 88 2 : 8 : 18 : 32 : 18 : 8 : 2

7. Group 3 The  group 3A elements  are the chemical elements that belong to group IIIA (3A) on the periodic table. Group 3a elements belong to the  boron family , which is a series of elements that occupy the 13th column on the periodic table. The reason why the boron family is called by this name is because the first element in group 3A is boron. The following list summarizes the elements in group 3A: Boron (B). Aluminum (al). Gallium (ga). Indium (in). Thallium ( tl ). Group 3A primarily consists of metal elements, with the exception of boron, which is a metalloid. Metalloids can be thought of as elements with a weak metallic character. They are capable of conducting electric and thermal energy, but not as well as most metals can. Metals are always  electropositive . They tend to give up their  valence electrons , which are the electrons present in an atom's outermost shell, to form positively charged  cations . Cations are positively charged ion

8. Group 1A  metals are alkali metals. They have only one valence electron in their outermost shell. The oxidation state of these metals is always +1. Group 2a  metals are alkaline earth metals. They have two valence electrons in their outermost shell. The oxidation state of these metals is always +2. Group 3a  metals are other metals. They have three valence electrons in their outermost shell. The oxidation state of each element varies.

9. Group 4 Group 4  is the second group of  transition metals  in the periodic table. It contains the four elements  titanium  ( ti ),  zirconium  ( zr ),  hafnium  (hf), and  rutherfordium  (rf). The group is also called the  titanium group  or  titanium family  after its lightest member. As is typical for early transition metals, zirconium and hafnium have only the group  oxidation state of +4 as a major one, and are quite electropositive and have a less rich coordination chemistry.

10. halogen A halogen is  a chemical element that forms a salt when it reacts with metal. Halogens are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid and Iodine and astatine are solids. Halogens are very reactive, the reactivity decreases from fluorine to astatine. Table salt, bleach, fluoride in toothpaste, and chlorine in swimming pools, halogen lamps. All involve one or more of the halogens, which form the elements in Group 7, or (17) of the periodic table.

11. Occurences of the elements Among the alkali metals sodium and  potassium  are abundant and lithium, rubidium and caesium have lower abundance. Francium is highly radioactive. Beryllium is found in small quantities as silicate minerals, phenacite, Be2SiO4, and beryl, Be3Al2S6O8. Beryllium is not very abundant, probably because it is difficult to extract. Magnesium and calcium compounds formed by the weathering of igneous rocks, found in all soils and in most fresh waters as hydrogen trioxocarbonates (IV), tetraoxosulphates (VI) and chlorides, causing hardness of water. Calcium is found in bones as the double salt, 3Ca3 (PO4)2.CaCO3.H2O and as calciumtrioxocarbonate (IV), CaCO3, in egg shells and seashells. Calcium occurs as the trioxocarbonate (IV), CaCO3, in limestone, marble, chalk, aragonite, coral and calcite.

12. Physical properties The group of halogens is the only periodic table group that contains elements in all three familiar states of matter at standard temperature and pressure Fluorine (F) is a pale yellow gas, its melting point is -219.62°C, and its boiling point is -188.14°C. Fluorine’s relative density is 1.108. Low melting and boiling points Chlorine (cl) is a greenish gas Bromine ( br ) is a dark red liquid Iodine (I) is a black solid, and when heated, it forms a purple vapour Astatine (at) is a black solid The halogens have a strong and often nasty smell The halogen elements are extremely toxic They are poor conductors of heat and electricity Halogens have seven valence electrons; because halogens have one electron missing, they form negative ions and are highly reactive. The common physical properties of the elements are melting points, boiling points, density, 

13. chemical properties Halogens have seven valence electrons; because halogens have one electron missing, they form negative ions and are highly reactive. They can gain an electron by reacting with atoms of other elements. Fluorine is one of the most reactive elements in existence. They have relatively weak intermolecular forces. One of the definitive properties of halogens is that they are highly reactive. Due to this nature, they can form different compounds such as halides, interhalogens and polyhalogenated compounds.

14. chemical properties Hydrogen Halides These are binary compounds formed when halogens react with hydrogen. Generally, if we take fluorine, chlorine, and bromine, the reaction appears in the form given below: H 2  + X 2  → 2HX Hydrogen halides are strong hydrohalic acids when dissolved in water. These acids are dangerous. Metal Halides These are compounds formed by the reaction of halogens with metals. Metal halides can be highly ionic compounds, monomeric covalent compounds or polymeric covalent compounds. They are usually obtained through direct combination or through the neutralisation of a basic metal salt with hydrohalic acid.