REVIEW: Parts of the Atom Electron Orbit Neutron Proton Nucleus

Element, Compound, or Mixture? ELEMENTCOMPOUNDELEMENT MIXTURECOMPOUND MIXTURE

Review of the Periodic Table titanium What is the symbol for Titanium? _________ What is the atomic number of titanium? _________ How many protons does titanium have? _________ How many electrons does a neutral titanium atom have? __________ What is the atomic weight for titanium? _______________ Ti

Author: J R Reid The Periodic Table The Periodic table as we know it today was arranged by a Russian Chemist named Mendeleev. He arranged it according to the physical and chemical properties of the elements

WORKSHEET 1 Complete the handout by writing the missing chemical symbols in each box. ON your periodic table (given last lesson) Label the following: Alkali Alkaline Metals Transition Metals Poor metals Halogens Noble gases Non metals

halogens

Arranging Elements It is arranged in rows (across) called Periods and columns (down) called Groups Groups of elements show certain trends – they have similar properties Groups Periods

Author: J R Reid Trends On The Periodic Table

Atomic Size Atoms have certain sizes depending on: The amount of electrons (negatives) The pull from the nucleus (positive protons) For the third period (row) the atomic radius for each atom gets smaller across the table Even though the atoms have got more electrons their electronegativity (pull for electrons) is increasing because of increasing number of protons NaMgAlSiPSClAr

NaMgAlSiPSClAr Electronegativity Electronegativity is the ability of a nucleus to attract its valence/bonding electrons. It follows certain trends on the table: As you go across (left to right) it gets stronger As you go up it gets stronger e K e- What do you notice about the atomic number as you go across the period? What about the number of orbitals as you go across the period? What about the number of orbitals as you go down a group? 19

Increasing size Size

Trends From Left to Right Proton number and Atomic Mass increases Atomic size decreases (more protons pulling the electrons) Oxidising ability increases Form ionic compounds to forming covalent compounds Melting Points from relatively high to relatively low Form positive ions to form negative ions

Trends down a group Proton number and Atomic Mass increases Atomic size increases (adding more orbitals) Metals become more reactive Non-metals become less reactive

Valence Electrons Valence electrons (also known as valence) are the number of electrons present in the outer most orbital. What is the valence of this sodium atom? What is the valence of this chorine atom?

Valence Electrons The number of valence electrons of an element is determined by its periodic table group in which the element is categorized.