Elements and Atoms Atoms, Bonding and the Periodic Table Ionic BondsCovalent BondsMixed Bag

How are compounds and mixtures different?

Compounds are 2 or more elements chemically combined, while mixtures are two or more substances not chemically combined.

What particle(s) are found in the nucleus of an atom?

proton and neutron

What are the simplest pure substances that cannot be broken down into any other substances? Name two examples!

Elements (ex. hydrogen, copper, neon)

Rutherfod’s experiment using gold foil helped make what discovery about the structure of the atom?

Positive charges must be clustered in the center of the atom called the nucleus.

How many times larger can the diameter of an actual atom be compared to its nucleus? (penny activity!)

100,000 times

What does the electron dot diagram show?

How many valence electrons the element has.

Why are the noble gases very stable?

They have a full outer shell of electrons.

On the periodic table, what do both the number above and below the element symbol each tell us about the element?

Above – atomic number; shows the number of protons (and electrons) Below – atomic mass; shows the mass of an element’s atom

Are the alkali metals (group on the periodic table) more likely to gain or lose valence electrons? Explain why?

Lose, because they have only 1 valence electron and it is easier to lose 1 than gain 7. (except for hydrogen)

How many valence electrons does phosphorus have? (atomic number 15)

5 valence electrons (2, 8, 5)

When an atom loses an electron, it becomes a (positive or negative) ion?

Positive – because it lost a negative

Do ionic compounds have (high or low) melting points. Explain why.

High melting points – because ionic bonds are strong because of their crystal structure. Thus, it takes more heat to break the ionic bonds apart.

Use the chart to write the formula for lithium oxide.

Li 2 O lithium oxide

What are polyatomic ions?

Ions that are made up of more than one atom. BONUS POINT: Is aluminum or is carbonate polyatomic?

Explain why salt, when dissolved in water, conducts electricity? Why does it not conduct as a solid?

Salt conducts electricity in solution because it is made up of ions and ions carry an electrical charge. In water, ions bonds break apart and move around freely allowing them to conduct electricity. As a solid, these ions are not moving around freely enough to conduct electricity.

What do you call a group of atoms joined by covalent bonds?

molecule

Why type of bonds are shown below? Also, how many of these bonds are there?

Two double bonds

Describe the conductivity of molecular compounds.

Poor – there are no charged particles available to move, so electricity cannot flow.

Why are some covalent bonds polar?

Because some atoms have a larger nucleus (atomic mass) which gives it a slightly stronger pull on the valence electrons being shared.

In a hydrogen fluoride molecule, which atom has the slight positive charge?

Hydrogen – because it has a smaller pull than fluorine on the shared electrons.

What the symbol for sodium?

Na

Which has a lower melting point – water or magnesium chloride? WHY?

Water – Water is a molecular compound while magnesium chloride is an ionic compound. Forces between molecules are weaker than forces between ions in ionic compounds. Thus, it takes less heat to melt molecular compounds.

How does an ion of alumnium with a charge of 3+ form?

It loses 3 electrons.

Why was tap water not used when testing all the substances in our “Shedding Light on Ions” lab?

Tap water contains a small amount of ions from the minerals and other substances that are mixed into the water.

Whose atomic model was compared to raisins or berries scattered about in a muffin?

J. J. Thomson – a British scientist

FINAL JEOPARDY Periodic Table

Name the element each symbol below represents: Ne, Li, Na, S, K, Kr