Science chapter 6
Metallic bonds
Draw a Conclusion A sample of an element can be drawn easily into wire and con ducts electricity well. What kind of bonds can you conclude are present?
An electron cloud shows the areas probably occupied by electrons moving around the nucleus. An electron dot diagram shows the number of electrons in the outer energy level (valence electrons).
Electron cloud- electron dot diagram
An electron dot diagram tells the number of electrons in an atom's outer energy level. If one or more of those electrons are lost or gained, an ion is formed.
Electron dot diagram- ion
The negative parts of water molecules are attracted to the positive parts of other water molecules. Because of these attractions, more energy is required to separate the molecules.
Explain Use the fact that water is a polar molecule to explain why water has a much higher boiling point than other molecules of its size.
Elements in Groups 1 and 2 lose one or two electrons easily. Elements in Groups 16 and 17 gain one or two electrons easily.
ExplainwhyGroups1and2formmany compounds with Groups 16 and 17.
There are two oxygen atoms
In the chemical formula C 0 2, the sub script 2 shows which of the following?
The outer electrons in cesium is farther from the nucleus so easier to remove from the atom making it more reactive.
Interpret Data Both cesium, in period 6, and lithium, in period 2, are in the alkali met als family. Cesium is more reactive. Explain this using the energy step diagram in Figure 4.
An ion is a charged atom, whereas a molecule is two or more atoms covalently bonded with each other.
Ion-molecule
An ionic bond forms when positively and negatively charged ions are attracted to each other. A covalent bond occurs when two or more atoms share electrons.
Ionic bond-covalent bond
Metallic bonds form between metal atoms when they pool electrons. Ionic bonds form between a metal and a non metal.
Metallic bond-ionic bond
A molecule contains atoms joined by covalent bonds whereas a compound contains two or more elements joined by covalent or ionic bonds.
Molecule-compound
CuCl will produce more copper because it has a higher proportion of copper than CuCl2.
Predict If equal masses of CuCl and CuCl2 decompose into their components— copper and chlorine—predict which com pound will yield more copper. Explain.
The electrons are shared unequally. The electrons spend more time near the fluorine atom than the hydrogen atom.
Predict In the HF molecule above, predict if the electrons are shared equally or unequally between the two atoms. Where do the electrons spend more of their time?
The lowest energy level can have only two electrons. Since this energy level is helium's outer level, it is full with two electrons.
Recognize Cause and Effect A helium atom has only two electrons. Why does helium behave as a noble gas?
They are shared unequally
What happens to electrons in the forma tion of a polar covalent bond?
18
What is the number of the group in which the elements have a stable outer energy level?
It is an ionic compound
Which is NOT true about the molecule h 2o?
CO
Which of the following compounds is unlikely to contain ionic bonds?
A negative ion
Which of the following describes what is represented by the symbol Cl- ?
Cl2
Which of the following is a covalently bonded molecule?
Molecules
Which term describes the units that make up compounds with covalent bonds?
Ions
Which term describes the units that make up substances formed by ionic bonding?
The positive ends of a polar water molecule are attracted to the chloride ions and pull them out of the solid. The negative ends of the polar water molecules are attracted to the sodium ions and pull them out of the solid.
Analyze When salt dissolves in water, the sodium and chloride ions separate. Explain why this might occur.
A molecule is made up of covalently bonded atoms. It can be expressed by a chemical formula.
Chemical formula- molecule
A compound is a pure substance made up of two or more elements. Its formula shows what those elements are and in what proportion.
Compound-formula
Chemical Bond → Ionic, Metallic, and Covalent Ionic Bonds → form when → a metal loses an electron to a nonmetal → as in → NaCl Metallic Bonds → form when → atoms of a metal pool their electrons → as in → Ag Covalent Bonds → forms when two nonmetal share their electrons → unequally or equally Equally as in → HCl → which is → polar Unequally as in → H2 → which is → nonpolar
Concept Map Draw a concept map starting with the term Chemical Bond and use all the vocabulary words.
A polar bond is a type of covalent bond where electrons are shared unequally
Covalent bond- polar bond