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Elements, Atoms, and Ions

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Presentation on theme: "Elements, Atoms, and Ions"— Presentation transcript:

1 Elements, Atoms, and Ions

2 The Language of Chemistry
_________________________- pure substances that cannot be decomposed by ordinary means to other substances. Aluminum Bromine Sodium

3 The Language of Chemistry
The elements, their names, and symbols are given on the _____________ How many elements are there?

4 The Periodic Table Dmitri Mendeleev ( )

5 The Atom An atom consists of a _____________________
(of protons and neutrons) _________________ in space about the nucleus. Electron cloud Nucleus

6 Composition of molecules is given by a ______________________
A ______________ is the smallest unit of a compound that retains the chemical characteristics of the compound. Composition of molecules is given by a ______________________ H2O C8H10N4O2 - caffeine

7 Copper atoms on silica surface.
An ___________ is the smallest particle of an element that has the chemical properties of the element. Copper atoms on silica surface. Distance across = 1.8 nanometer (1.8 x 10-9 m)

8 _________________are composed of atoms and so can be decomposed to those atoms.
The red compound is composed of • nickel (Ni) (silver) • carbon (C) (black) • hydrogen (H) (white) • oxygen (O) (red) • nitrogen (N) (blue)

9 Compounds __________________ __________________ __________________
properties differ from those of individual elements EX: table salt (NaCl)

10 ATOMIC COMPOSITION ________________________ (p+)
+ electrical charge mass = x g relative mass = atomic mass units (amu) but we can round to 1 _________________________ (e-) negative electrical charge relative mass = amu but we can round to 0 _________________________ (no) no electrical charge mass = amu but we can round to 1

11 IONS ______________________ are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom gives a ______________________with a positive charge Adding an electron to an atom gives an _____________________ with a negative charge. To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na+ Ca+2 I- O-2 Na Ca I O

12 Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to N would like to O would like to Gain 4 electrons Gain 3 electrons Gain 2 electrons

13 IONIC BOND __________________________________________________________________

14 Ionic Bonds: One Big Greedy Thief Dog!

15 COVALENT BOND __________________________________________________________________

16 Covalent Bond Between nonmetallic elements of similar electronegativity. _______________________________________________________ Stable non-ionizing particles, they are not conductors at any state Examples; O2, CO2, C2H6, H2O, SiC

17 ______________________________________________________
NONPOLAR COVALENT BONDS ______________________________________________________ H2 or Cl2

18 2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons.
Oxygen Atom Oxygen Atom Oxygen Molecule (O2)

19 ______________________________________________________
POLAR COVALENT BONDS ______________________________________________________ H2O

20 Polar Covalent Bonds: Unevenly matched, but willing to share.

21 - water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.


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