Chemical bonds

Июль 30, 2022

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Chemical bonds

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2. Atom – the smallest unit of matter “indivisible” Helium atom
3. electron shells Atomic number = number of Electrons Electrons vary in the amount of energy they
4. Electrons are placed in shells according to rules: The 1st shell can hold up to two
5. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8
6. Why are electrons important? Elements have different electron configurations different electron configurations mean different levels of
9. Electron Dot Structures Symbols of atoms with dots to represent the valence-shell electrons 1 2 13
10. Chemical bonds: an attempt to fill electron shells Ionic bonds – Covalent bonds – Metallic bonds
11. Learning Check ● A. X would be the electron dot formula for 1) Na 2) K
12. IONIC BOND bond formed between two ions by the transfer of electrons
13. Formation of Ions from Metals Ionic compounds result when metals react with nonmetals Metals lose electrons
14. Formation of Sodium Ion Sodium atom Sodium ion Na ∙ – e− ⎯⎯→ Na + 2-8-1
15. Formation of Magnesium Ion Magnesium atom Magnesium ion ∙ Mg ∙ – 2e− ⎯→ Mg2+ 2-8-2
16. Some Typical Ions with Positive Charges (Cations) Group 1 Group 2 Group 13 H+ Mg2+ Al3+
17. Learning Check A. Number of valence electrons in aluminum 1) 1 e- 2) 2 e- 3)
18. Solution A. Number of valence electrons in aluminum 3) 3 e- B. Change in electrons for
19. Learning Check Give the ionic charge for each of the following: A. 12 p+ and 10
20. Ions from Nonmetal Ions In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from
21. Fluoride Ion unpaired electron octet ∙ ∙ ∙ ∙ 1 - : F ∙ + e−
22. Ionic Bond Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer
24. Ionic Bonds: One Big Greedy Thief Dog!
25. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance
27. COVALENT BOND bond formed by the sharing of electrons
28. Covalent Bond Between nonmetallic elements of similar electronegativity. Formed by sharing electron pairs Stable non-ionizing particles,
29. Covalent Bonds
30. Bonds in all the polyatomic ions and diatomics are all covalent bonds
31. when electrons are shared equally NONPOLAR COVALENT BONDS H2 or Cl2
32. 2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons. Oxygen Atom Oxygen
33. when electrons are shared but shared unequally POLAR COVALENT BONDS H2O
34. Polar Covalent Bonds: Unevenly matched, but willing to share.
35. - water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons
36. METALLIC BOND bond found in metals; holds metal atoms together very strongly
37. Metallic Bond Formed between atoms of metallic elements Electron cloud around atoms Good conductors at all
38. Metallic Bonds: Mellow dogs with plenty of bones to go around.
39. Ionic Bond, A Sea of Electrons
40. Metals Form Alloys Metals do not combine with metals. They form Alloys which is a solution
41. Formula Weights Formula weight is the sum of the atomic masses. Example- CO2 Mass, C +
42. Practice Compute the mass of the following compounds round to nearest tenth & state type of
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Atom – the smallest unit of matter “indivisible”
Helium
atom

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electron shells
Atomic number = number of Electrons
Electrons vary in the amount

of energy they possess, and they occur at certain energy levels or electron shells.
Electron shells determine how an atom behaves when it encounters other atoms

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Electrons are placed in shells according to rules:
The 1st shell can

hold up to two electrons, and each shell thereafter can hold up to 8 electrons.

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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

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Why are electrons important?
Elements have different electron configurations
different electron configurations mean

different levels of bonding

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Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell

electrons
1 2 13 14 15 16 17 18
H∙ He:
∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙
Li∙ Be∙ ∙ B ∙ ∙ C ∙ ∙ N ∙ ∙ O ∙ : F ∙ :Ne :
∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙
∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙
Na∙ Mg∙ ∙ Al∙ ∙ Si ∙ ∙P∙ ∙S∙ :Cl ∙ :Ar :
∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙

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Chemical bonds: an attempt to fill electron shells
Ionic bonds –
Covalent

bonds –
Metallic bonds

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Learning Check
●
A. X would be the electron dot formula

for
1) Na 2) K 3) Al
● ●
B. ● X ● would be the electron dot formula
●
1) B 2) N 3) P

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IONIC BOND bond formed between two ions by the transfer of electrons

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Formation of Ions from Metals
Ionic compounds result when metals react with

nonmetals
Metals lose electrons to match the number of valence electrons of their nearest noble gas
Positive ions form when the number of electrons are less than the number of protons
Group 1 metals ⎯→ ion 1+
Group 2 metals ⎯→ ion 2+
Group 13 metals ⎯→ ion 3+

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