Date: October 7, 2015

Aim #14: What determines an atom’s reactivity?

HW:1)Worksheet- Practice with Atoms and Ions2)Textbook Guided Reading 2-1 due Tuesday

10/13

Do Now: Warm-Up Notebook

Date Title of Activity Page #10/7 Analyzing Chemical Formulas 26

Meet the Elementshttps://www.youtube.com/watch?v=d0zION8xjbM

Review of Atoms:

PN

Nucleus (protons and neutrons)

Electrons

The protons and neutrons have a much greater mass thanthe electrons.

Where are the electrons?

The electrons continually move around the nucleusat great speed. The attraction between the (-) charged electrons and the(+) charged protons keeps the electrons close to nucleus.

What are the differences between elements?

An important difference among elements is the #of protons in their atoms.Atomic Number – the number of protons of an element.

What is the atomicnumber of Helium?

2

Can we find this information on the Periodic Table?

**Notice, that no two elements have the same atomicnumber.

Atoms tend to be electrically neutral

What does that mean?

Atoms, if left alone, typically have the same numberof protons and electrons.

How many protons should thisatom have if it is electricallyneutral?

What is its atomic number?11

11

What is an Ion?An atom that has a positiveor negative charge due toa loss or gain ofELECTRONS!

Cation (+ Ion) – due to loss of an electron.

Anion (- Ion) – due to gain of an electron.

Brain Pop- Ions

https://www.brainpop.com/science/matterandchemistry/ions/

Atomic Number vs. Mass NumberThe atomic number is the number of protons foundin an element.The mass number is the number of protons plus thenumber of neutrons.

What is the mass number of Carbon?

How many protons does Oxygen have?

12

8

How many neutrons does Sodium have? 11

Mass number = protons + neutrons

Date: October 8, 2015

Aim #14: What determines an atom’s reactivity?

HW:1)Worksheet- Practice with Ions and Isotopes2)Textbook Guided Reading 2-1 due Tuesday

10/13

Do Now: Warm-Up Notebook

Date Title of Activity Page #10/8 Simple Chemistry Review 27

What is an Isotope?

Isotopes of an element have the same number ofprotons in their atoms but different numbers ofneutrons.

C-12 C-13 C-14Mass Number

Brain Pop- Isotopes

https://www.brainpop.com/science/matterandchemistry/isotopes/

Practice Problems

1)How many protons in O-17?

2)What is the atomic number of C-13?

3) What element has an atomic number of 7?

4) What is the mass number of an element with8 protons, 6 electrons, and 6 neutrons?

5) How many electrons does C-14 have?

8

6

N

14

6

What determines an atom’s reactivity? Electrons

Usually it is the electrons in the highest energy levelof an atom that determine how that atom reacts

1st energy level(2 electrons max)

2nd energy level(8 electrons max)

1st energy level(2 electrons max)

How do we know if an element is reactive?

If an element has partly-filled outer energy levels

This condition makes these elements chemicallyreactive.

Rules in filling energy levels:

1)Determine the number of electrons the atom has.

2)Remember, the 1st energy level can hold 2 electrons and the 2nd energy level can hold 8 electrons.

3) Fill the lowest energy levels first.

Practice Problems:

1)If an atom has 9 electrons, how many electrons are in the second energy level?

2)Is He a reactive element? Why?

3)How many free spaces are present in the second level of F?

7

No

1