2nd 9 weeks ps

Ions and Ion Charges

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Multiple Choice

Pre-Check:

Why is the element sodium have a charge of zero?

• There are 12 neutrons.

• It has 11 p+ and 11 e-.

• It has 11 p+ and 10 e-.

Ions help nerves send impulses.

• Nerve impulses are required for moving muscles.

• Example: Your heart beats because nerve impulses are sent from your brain to heart muscles.

EKGs measure nerve impulses within your heart muscles by voltage.

• Voltage is a measure of the + and - charges across a material, like a battery.

Multiple Choice

What happens to the voltage (mV) over time as the heart is beating?

• The voltage stays the same.

• The voltage increases and decreases.

Open Ended

Hypothesis:

What do you think causes the voltage to change in a beating heart? (Use your prior knowledge; Guess if you cannot think of anything.)

Ions are elements with a positive (+) or negative (-) charge.

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By themselves, elements are neutral.

• You have learned that elements contain the same # of protons (p+) and electrons (e-).

• Example: Sodium (Na) 11 p+ & 11 e-

Atoms want to have a "full" outer shell (orbital) of 8 electrons.

Hydrogen (H) and Helium (He) are the only exceptions- They have 2 in the first shell (orbital).

Multiple Choice

Sodium (Na) has 1 electron (e-) in its outer shell (orbital). How can it make a full outer shell? (HINT: Think of which option would be "easier" for the atom.)

• Giving away or donating the outer electron.

• Taking on or accepting 7 more electrons.

Sodium (Na) will give away its electron to an element like Chlorine (Cl).

• The picture only shows the outer shell (orbital) of Na and Cl.

• Chlorine has 7 e-, so its easier to take on 1 e- to make a full 8 e- in its outer shell.

Sodium (Na) is in Group 1 (red) on the Periodic Table.

All elements in Group 1 will give away or DONATE 1 e- to make a full outer shell.

Chlorine (Cl) is in Group 17 (Green) on the periodic table.

All elements in Group 17 will ACCEPT 1e- to make a full outer shell.

Chlorine (Cl) is in Group 17 (Green) on the periodic table.

All elements in Group 17 will ACCEPT 1e- to make a full outer shell.

Multiple Choice

Knowledge Check:

Why does Sodium become a +1 charge?

• Sodium gives away 1 e-, so it now has 1 less negative (-) charge.

• Sodium accepts 1 e-, so it now has 1 more negative (-) charge.

Multiple Choice

Knowledge Check:

Why does Chlorine (Cl) become a -1 charge?

• Cl donates an e-, so it now has 1 less negative (-) charge.

• Cl accepts an e-, so it now has 1 more negative (-) charge.

Multiple Choice

Which of the following would donate 1 e- and become a +1 charge like Na? (HINT: Find Group 1)

• Li

• He

Multiple Choice

Which of the following would accept 1 e- and become a -1 charge like Cl? (HINT: Find Group 17)

• F

• Ne

Open Ended

What do you think the body uses to increase (+) or decrease (-) voltages for nerve impulses? Use what you have learned about ions in this lesson to help answer this question. Take an guess.