Dot also should be allowed in Pattern

Question

Hi

 In below code i want User can enter . (Dot) also in pattern.

                                        <div class="col-lg-6 col-md-6 col-sm-12">
                                            <div class="form-group">
                                                <label>Department Name</label>&nbsp;<span style="color: red">*</span>
                                                <asp:TextBox ID="txtDepartmentName" MinLength="2" MaxLength="50" class="form-control" placeholder="Department Name" required="true"
                                                    pattern="[a-zA-Z\s]*" title="Valid characters: Alphabets and Space." runat="server"></asp:TextBox>
                                            </div>
                                        </div>

Thanks