Question

do now: the periodic table (11th grade chemistry)
name: madison clarke date: oct 29th
directions: answer the following questions in your notebook or on this sheet.
you have 5 minutes to complete this activity.

1. what does the atomic number of an element represent?

it represents

1. how does the number of protons relate to the elements identity?
2. what trend do you notice in atomic size as you move from left to right across a period?
3. what do elements in the same group (column) of the periodic table have in common?
4. the element chlorine (cl) is in group 17 and period 3.

○ predict one property it might share with fluorine (f).

1. bonus: what is the difference between an alkali metal and an alkaline earth metal in terms of reactivity.

Explanation:

1. The atomic number of an element represents the number of protons in the nucleus of an atom of that element.
2. The number of protons determines the element's identity. Each element has a unique number of protons.
3. As you move from left to right across a period, the atomic size generally decreases. This is because the number of protons (and thus the nuclear charge) increases, pulling the electrons closer to the nucleus.
4. Elements in the same group (column) of the periodic table have the same number of valence electrons. This gives them similar chemical properties.
5. Chlorine (Cl) and fluorine (F) are both in group 17 (halogens). One property they might share is high reactivity. Halogens are very reactive non - metals.
6. Alkali metals (group 1) are more reactive than alkaline earth metals (group 2). Alkali metals have one valence electron, which they lose easily. Alkaline earth metals have two valence electrons, and they are less willing to lose these electrons compared to alkali metals.

Answer:

1. The number of protons in the nucleus of an atom of that element.
2. The number of protons determines the element's identity (each element has a unique number of protons).
3. Atomic size generally decreases.
4. The same number of valence electrons (similar chemical properties).
5. High reactivity (as they are both halogens).
6. Alkali metals (group 1) are more reactive than alkaline earth metals (group 2) as alkali metals have one valence electron (lost easily) and alkaline earth metals have two valence electrons (less easily lost).